Chemically amplified positive-type photosensitive resin composition

ABSTRACT

A chemically amplified positive-type photosensitive resin composition capable of forming a resist pattern having a nonresist portion with a favorable rectangular sectional shape, a method of manufacturing a resist pattern using the composition, a method of manufacturing a substrate with a template using the composition, and a method of manufacturing a plated article using the substrate with a template manufactured by the method. In a chemically amplified positive-type photosensitive resin composition including an acid generator, a resin whose solubility in alkali increases under the action of acid, and an organic solvent, an acrylic resin is used that includes a constituent unit derived from an acrylic acid ester including an —SO2-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group including an aromatic group and an alcoholic hydroxyl group.

RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2016-091292 filed Apr. 28, 2016, the entire content of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a chemically amplified positive-type photosensitive resin composition, a method of manufacturing a resist pattern using the chemically amplified positive-type photosensitive resin composition, a method of manufacturing a substrate with a template using the chemically amplified positive-type photosensitive resin composition, and a method of manufacturing a plated article using the substrate with a template manufactured by the method.

Related Art

Photofabrication is now the mainstream of a microfabrication technique. Photofabrication is a generic term describing the technology used for manufacturing a wide variety of precision components such as semiconductor packages. The manufacturing is carried out by applying a photoresist composition to the surface of a processing target to form a photoresist layer, patterning this photoresist layer using photolithographic techniques, and then conducting chemical etching, electrolytic etching, and/or electroforming based mainly on electroplating, using the patterned photoresist layer (resist pattern) as a mask.

In recent years, high density packaging technologies have progressed in semiconductor packages along with downsizing electronics devices, and the increase in package density has been developed on the basis of mounting multi-pin thin film in packages, miniaturizing of package size, two-dimensional packaging technologies in flip-tip systems or three-dimensional packaging technologies. In these types of high density packaging techniques, connection terminals, including protruding electrodes (mounting terminals) known as bumps that protrude above the package or metal posts that extend from peripheral terminals on the wafer and connect rewiring with the mounting terminals, are disposed on the surface of the substrate with high precision.

In the photofabrication as described above, a photoresist composition is used, and chemically amplified photoresist compositions containing an acid generator have been known as such a photoresist composition, (see Patent Documents 1, 2 and the like). According to the chemically amplified photoresist composition, an acid is generated from the acid generator upon irradiation with radiation (exposure) and diffusion of the acid is promoted through heat treatment, to cause an acid catalytic reaction with a base resin and the like in the composition resulting in a change to the alkali-solubility of the same.

Further, photoresist compositions for use in the photofabrication are also known (see, for example, Patent Document 3). Photoresist compositions disclosed in Patent Document 3 are used, for example, in the formation of bumps and metal posts by a plating step. For example, a thick photoresist layer having a film thickness of about 20 μm is formed on a support, and the photoresist layer is exposed through a predetermined mask pattern and is developed. Thereby, a resist pattern in which portions for forming bumps or metal posts have been selectively removed (stripped) is formed. Then, bumps or metal posts can be formed by embedding a conductor such as copper into the removed portions (nonresist sections) using plating, and then removing the surrounding residual resist pattern.

Patent Document 1: Japanese Unexamined Patent Application, Publication No. H9-176112

Patent Document 2: Japanese Unexamined Patent Application, Publication No. H11-052562

Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2010-185986

SUMMARY OF THE INVENTION

For use in photofabrication applications as well as in other various applications, a resist pattern having a rectangular cross-sectional shape at a portion removed upon development (nonresist section) is usually desired, in a case where the resist pattern is formed with a photoresist composition for thick-film application.

Photoresist compositions as disclosed in Patent Document 3 are in many cases used as diluted with a solvent. The formation of a resist pattern using a solvent-containing photoresist composition, however, poses a problem that, in a cross section of a resist pattern as observed from a direction perpendicular to a planar direction of the resist pattern, the width of a nonresist portion is likely to be narrowed by the protrusion of the resist portion towards the nonresist portion side around the substrate. Thus, the protrusion of the resist portion towards the nonresist portion side around the substrate is called “footing”. In this case, in the formation of bumps or metal posts using a resist pattern as a template, the area of contact between the formed bumps or metal posts and the substrate is so small that the bumps or the metal posts may fall or be separated from the substrate.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a chemically amplified positive-type photosensitive resin composition capable of forming a resist pattern having a nonresist portion with a favorable rectangular sectional shape, a method of manufacturing a resist pattern using the chemically amplified positive-type photosensitive resin composition, a method of manufacturing a substrate with a template using the chemically amplified positive-type photosensitive resin composition, and a method of manufacturing a plated article using the substrate with a template manufactured by the method.

The present inventors have found that the above problems can be solved by using, in a chemically amplified positive-type photosensitive resin composition comprising an (A) acid generator that produces an acid by being irradiated with an active ray or radiation, a (B) resin whose solubility in alkali increases under the action of acid, and an (S) organic solvent, an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group, which has led to the completion of the present invention.

According to a first aspect of the present invention, there is provided a chemically amplified positive-type photosensitive resin composition, comprising an (A) acid generator that produces an acid by being irradiated with an active ray or radiation, a (B) resin whose solubility in alkali increases under the action of acid, and an (S) organic solvent,

wherein the (B) resin whose solubility in alkali increases under the action of acid contains an alkali-soluble group protected by an aliphatic acid-dissociable dissolution-inhibiting group, and

comprises an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group.

According to a second aspect of the present invention, there is provided a method of manufacturing a resist pattern, comprising:

laminating a photosensitive resin layer on a substrate, the layer comprising the chemically amplified positive-type photosensitive resin composition according to the first aspect of the present invention,

exposing the photosensitive resin layer through irradiation with an active ray or radiation, and developing the exposed photosensitive layer.

According to a third aspect of the present invention, there is provided a method of manufacturing a substrate with a template, comprising:

laminating a photosensitive resin layer on a metal substrate, the layer comprising the chemically amplified positive-type photosensitive resin composition according to the first aspect which is used for preparation of a template for plated article formation, exposing the photosensitive resin layer through irradiation with an active ray or radiation, and developing the exposed photosensitive layer to prepare a template for plated article formation.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a plated article, comprising plating the substrate with a template manufactured by the method according to the third aspect to form the plated article inside the template.

The present invention can provide a chemically amplified positive-type photosensitive resin composition capable of forming a resist pattern having a nonresist portion with a favorable rectangular sectional shape, a method of manufacturing a resist pattern using the chemically amplified positive-type photosensitive resin composition, a method of manufacturing a substrate with a template using the chemically amplified positive-type photosensitive resin composition, and a method of manufacturing a plated article using the substrate with a template manufactured by the method.

DETAILED DESCRIPTION OF THE INVENTION

<<Chemically Amplified Positive-Type Photosensitive Resin Composition>>

The chemically amplified positive-type photosensitive resin composition (hereinafter also referred to as the “photosensitive resin composition”) contains an (A) acid generator capable of producing an acid when irradiated with an active ray or radiation (hereinafter also referred to as the (A) acid generator), a (B) resin whose solubility in alkali increases under the action of acid (hereinafter also referred to as the (B) resin), and an (S) organic solvent. The photosensitive resin composition may comprise one or more components selected from a (C) alkali-soluble resin and a (D) acid diffusion suppressing agent, if desired.

The layer thickness of the resist pattern formed using the photosensitive resin composition is not particularly limited. Preferably, however, the photosensitive composition is preferably used for the formation of a thick resist pattern. The film thickness of a resist pattern formed with the photosensitive resin composition is 10 μm or more, preferably 10 to 150 μm, more preferably 20 to 120 μm, and in particular preferably 20 to 100 μm.

<(A) Acid Generator>

The (A) acid generator is a compound capable of producing an acid when irradiated with an active ray or radiation, and is not particularly limited as long as it is a compound which directly or indirectly produces an acid under the action of light. The (A) acid generator is preferably any one of the acid generators of the first to fifth aspects that will be described below. Hereinafter, suitable examples among the (A) acid generators that are suitably used in photosensitive resin compositions will be described as the first to fifth aspects.

The first aspect of the (A) acid generator may be a compound represented by the following formula (a1).

In the formula (a1), X^(1a) represents a sulfur atom or iodine atom respectively having a valence of g; g represents 1 or 2. h represents the number of repeating units in the structure within parentheses. R^(1a) represents an organic group that is bonded to X^(1a), and represents an aryl group having 6 to 30 carbon atoms, a heterocyclic group having 4 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, or an alkynyl group having 2 to 30 carbon atoms, and R1a may be substituted with at least one selected from the group consisting of an alkyl group, a hydroxyl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an arylthiocarbonyl group, an acyloxy group, an arylthio group, an alkylthio group, an aryl group, a heterocyclic group, an aryloxy group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkyleneoxy group, an amino group, a cyano group, a nitro group, and halogen atoms. The number of R^(1a)s is g+h(g−1)+1, and the R^(1a)s may be respectively identical to or different from each other. Furthermore, two or more R^(1a)s may be bonded to each other directly or via —O—, —S—, —SO—, —SO₂—, —NH—, —NR^(2a)—, —CO—, —COO—, —CONH—, an alkylene group having 1 to 3 carbon atoms, or a phenylene group, and may form a ring structure containing X^(1a). R^(2a) represents an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

X^(2a) represents a structure represented by the following formula (a2). —X^(4a)

X^(5a)—X^(4a)

_(h)  (a2)

In the formula (a2) X^(4a) represents an alkylene group having 1 to 8 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a divalent group of a heterocyclic compound having 8 to 20 carbon atoms, and X^(4a) may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, a hydroxyl group, a cyano group, a nitro group, and halogen atoms. X^(5a) represents —O—,—S—,—SO—,—SO2-,—NH—,—NR^(2a)—,—CO—,—COO—,—CONH—, an alkylene group having 1 to 3 carbon atoms, or a phenylene group.

h represents the number of repeating units of the structure in parentheses. X^(4a) s in the number of h+1 and X^(5a)s in the number of h may be identical to or different from each other. R^(2a) has the same definition as described above.

X^(3a−) represents a counterion of an onium, and examples thereof include a fluorinated alkylfluorophosphoric acid anion represented by the following formula (a17) or a borate anion represented by the following formula (a18). [(R^(3a))_(j)PF_(6-j)]⁻  (a17)

In the formula (a17), R^(3a) represents an alkyl group having 80% or more of the hydrogen atoms substituted by fluorine atoms.

j represents the number of R^(3a)s and is an integer from 1 to 5. R^(3a)s in the number of j may be respectively identical to or different from each other.

In the formula (a18) R^(4a) to R^(7a) each independently represents a fluorine atom or a phenyl group, and a part or all of the hydrogen atoms of the phenyl group may be substituted by at least one selected from the group consisting of a fluorine atom and a trifluoromethyl group.

Examples of the onium ion in the compound represented by the formula (a1) include triphenylsulfonium, tri-p-tolylsulfonium, 4-(phenylthio)phenyldiphenylsulfonium, bis[4-(diphenylsulfonio)phenyl]sulfide, bis[4-{bis[4-(2-hydroxyethoxy)phenyl]sulfonio}phenyl]sulfide, bis{4-[bis(4-fluorophenyl)sulfonio]phenyl}sulfide, 4-(4-benzoyl-2-chlorophenylthio)phenylbis(4-fluorophenyl) sulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthran-2-yldi-p-tolylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracen-2-yldiphenylsulfonium, 2-[(diphenyl)sulfonio]thioxanthone, 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldi-p-tolylsulfonium, 4-(4-benzoylphenylthio)phenyldiphenylsulfonium, diphenylphenacylsulfonium, 4-hydroxyphenylmethylbenzylsulfonium, 2-naphthylmethyl(1-ethoxycarbonyl)ethylsulfonium, 4-hydroxyphenylmethylphenacylsulfonium, phenyl[4-(4-biphenylthio)phenyl]-4-biphenylsulfonium, phenyl[4-(4-biphenylthio)phenyl]-3-biphenylsulfonium, [4-(4-acetophenylthio)phenyl]diphenylsulfonium, octadecylmethylphenacylsulfonium, diphenyliodonium, di-p-tolyliodonium, bis(4-dodecylphenyl)iodonium, bis(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium, bis(4-decyloxy)phenyliodonium, 4-(2-hydroxytetradecyloxy)phenylphenyliodonium, 4-isopropylphenyl(p-tolyl)iodonium, and 4-isobutylphenyl(p-tolyl)iodonium.

Among the onium ions in the compound represented by the formula (a1), a preferred onium ion may be a sulfonium ion represented by the following formula (a19).

In the formula (a19), R^(8a)s each independently represents a hydrogen atom or a group selected from the group consisting of alkyl, hydroxyl, alkoxy, alkylcarbonyl, alkylcarbonyloxy, alkyloxycarbonyl, a halogen atom, an aryl, which may be substituted, and arylcarbonyl. X^(2a) has the same definition as X^(2a) in the formula (a1).

Specific examples of the sulfonium ion represented by the formula (a19) include 4-(phenylthio)phenyldiphenylsulfonium, 4-(4-benzoyl-2-chlorophenylthio)phenylbis(4-fluorophenyl) sulfonium, 4-(4-benzoylphenylthio)phenyldiphenylsulfonium, phenyl[4-(4-biphenylthio)phenyl]-4-biphenylsulfonium, phenyl[4-(4-biphenylthio)phenyl]-3-biphenylsulfonium, [4-(4-acetophenylthio)phenyl]diphenylsulfonium, and diphenyl[4-(p-terphenylthio) phenyl]diphenylsulfonium.

In regard to the fluorinated alkylfluorophosphoric acid anion represented by the formula (a17), R^(3a) represents an alkyl group substituted with a fluorine atom, and a preferred number of carbon atoms is 1 to 8, while a more preferred number of carbon atoms is 1 to 4. Specific examples of the alkyl group include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl and octyl; branched alkyl groups such as isopropyl, isobutyl, sec-butyl and tert-butyl; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The proportion of hydrogen atoms substituted by fluorine atoms in the alkyl groups is usually 80% or more, preferably 90% or more, and even more preferably 100%. If the substitution ratio of fluorine atoms is less than 80%, the acid strength of the onium fluorinated alkylfluorophosphate represented by the formula (a1) decreases.

A particularly preferred example of R^(3a) is a linear or branched perfluoroalkyl group having 1 to 4 carbon atoms and a substitution ratio of fluorine atoms of 100%. Specific examples thereof include CF₃, CF₃CF₂, (CF₃)₂CF, CF₃CF₂CF₂, CF₃CF₂CF₂CF₂, (CF₃)₂CFCF₂, CF₃CF₂ (CF₃) CF, and (CF₃)₃C. j which is the number of R^(3a)s represents an integer from 1 to 5, and is preferably 2 to 4, and particularly preferably 2 or 3.

Preferred specific examples of the fluorinated alkylfluorophosphoric acid anion include [(CF₃CF₂)₂PF₄], [(CF₃CF₂)₃PF₃]⁻, [((CF₃)₂CF)₂PF₄]⁻, [((CF₃)₂CF)₃PF₃]⁻, [(CF₃CF₂CF₂)₂PF₄]⁻, [(CF₃CF₂CF₂)₃PF₃]⁻, [((CF₃)₂CFCF₂)₂PF₄]⁻, [((CF₃)₂CFCF₂)₃PF₃]⁻, [(CF₃CF₂CF₂CF₂)₂PF₄]⁻, and [(CF₃CF₂CF₂)₃PF₃]⁻. Among these, [(CF₃CF₂)₃PF₃]⁻, [(CF₃CF₂CF₂)₃PF₃]⁻, [((CF₃)₂CF)₃PF₃]⁻, [((CF₃)₂CF)₂PF₄]⁻, [((CF₃)₂CFCF₂)₃PF₃]⁻, and [((CF₃)₂CFCF₂)₂PF₄]⁻ are particularly preferred.

Preferred specific examples of the borate anion represented by the formula (a18) include tetrakis(pentafluorophenyl)borate ([B(C₆F₅)₄]⁻), tetrakis[(trifluoromethyl)phenyl]borate ([B(C₆H₄CF₃)₄]⁻), difluorobis(pentafluorophenyl)borate ([(C₆F₅)₂BF₂]⁻), trifluoro(pentafluorophenyl)borate ([(C₆F₅)BF₃]⁻), and tetrakis(difluorophenyl)borate ([B(C₆H₃F₂)₄]⁻). Among these, tetrakis(pentafluorophenyl)borate ([B(C₆F₅)₄]⁻) is particularly preferred.

The second aspect of the (A) acid generator include halogen-containing triazine compounds such as 2,4-bis(trichloromethyl)-6-piperonyl-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(2-furyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methyl-2-furyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-ethyl-2-furyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-propyl-2-furyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,5-dimethoxyphenyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,5-diethoxyphenyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,5-dipropoxyphenyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3-methoxy-5-ethoxyphenyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3-methoxy-5-propoxyphenyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,4-methylenedioxyphenyl)ethenyl]-s-triazine, 2,4-bis(trichloromethyl)-6-(3,4-methylenedioxyphenyl)-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)styrylphenyl-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)styrylphenyl-s-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(2-furyl)ethenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(5-methyl-2-furyl)ethenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(3,5-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(3,4-methylenedioxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, tris(1,3-dibromopropyl)-1,3,5-triazine and tris(2,3-dibromopropyl)-1,3,5-triazine, and halogen-containing triazine compounds represented by the following formula (a3) such as tris(2,3-dibromopropyl)isocyanurate.

In the formula (a3), R^(9a), R^(10a) and R^(11a) each independently represent a halogenated alkyl group.

Further, the third aspect of the (A) acid generator include α-(p-toluenesulfonyloxyimino)-phenylacetonitrile, α-(benzenesulfonyloxyimino)-2,4-dichlorophenylacetonitrile, α-(benzenesulfonyloxyimino)-2,6-dichlorophenylacetonitrile, α-(2-chlorobenzenesulfonyloxyimino)-4-methoxyphenylacetonitrile and α-(ethylsulfonyloxyimino)-1-cyclopentenylacetonitrile, and compounds represented by the following formula (a4) having an oximesulfonate group.

In the formula (a4), R^(12a) represents a monovalent, bivalent or trivalent organic group, R^(13a) represents a substituted or unsubstituted saturated hydrocarbon group, an unsaturated hydrocarbon group, or an aromatic compound group, and n represents the number of repeating units of the structure in the parentheses.

In the formula (a4), the aromatic compound group indicates a group of compounds having physical and chemical properties characteristic of aromatic compounds, and examples thereof include aryl groups such as a phenyl group and a naphthyl group, and heteroaryl groups such as a furyl group and a thienyl group may be exemplified. These may have one or more appropriate substituents such as halogen atoms, alkyl groups, alkoxy groups and nitro groups on the rings. It is particularly preferable that R^(13a) is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group. In particular, compounds in which R^(12a) represents an aromatic compound group, and R^(13a) represents an alkyl group having 1 to 4 carbon atoms are preferred.

Examples of the acid generator represented by the formula (a4), include compounds in which R^(12a) is any one of a phenyl group, a methylphenyl group and a methoxyphenyl group, and R^(13a) is a methyl group, provided that n is 1, and specific examples thereof include α-(methylsulfonyloxyimino)-1-phenylacetonitrile, α-(methylsulfonyloxyimino)-1-(p-methylphenyl)acetonitrile, α-(methylsulfonyloxyimino)-1-(p-methoxyphenyl)acetonitrile, [2-(propylsulfonyloxyimino)-2,3-dihydroxythiophene-3-ylidene](o-tolyl)acetonitrile and the like. Provided that n is 2, the acid generator represented by the formula (a4) is specifically an acid generator represented by the following formulae.

In addition, the fourth aspect of the (A) acid generator include onium salts that have a naphthalene ring at their cation moiety. The expression “have a naphthalene ring” indicates having a structure derived from naphthalene and also indicates at least two ring structures and their aromatic properties are maintained. The naphthalene ring may have a substituent such as a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxyl group, a linear or branched alkoxy group having 1 to 6 carbon atoms or the like. The structure derived from the naphthalene ring, which may be of a monovalent group (one free valance) or of a bivalent group (two free valences), is desirably of a monovalent group (in this regard, the number of free valance is counted except for the portions connecting with the substituents described above). The number of naphthalene rings is preferably 1 to 3.

Preferably, the cation moiety of the onium salt having a naphthalene ring at the cation moiety is of the structure represented by the following general formula (a5).

In the formula (a5), at least one of R^(14a), R^(15a) and R^(16a) represents a group represented by the following formula (a6), and the remaining represents a linear or branched alkyl group having 1 to 6 carbon atoms, a phenyl group which may have a substituent, a hydroxyl group, or a linear or branched alkoxy group having 1 to 6 carbon atoms. Alternatively, one of R^(14a), R^(15a) and R^(16a) is a group represented by the following formula (a6), and the remaining two are each independently a linear or branched alkylene group having 1 to 6 carbon atoms, and these terminals may bond to form a ring structure.

In the formula (a6), R^(17a) and R^(18a) each independently represent a hydroxyl group, a linear or branched alkoxy group having 1 to 6 carbon atoms, or a linear or branched alkyl group having 1 to 6 carbon atoms, and R^(19a) represents a single bond or a linear or branched alkylene group having 1 to 6 carbon atoms that may have a substituent.

l and m each independently represent an integer of 0 to 2, and l+m is no greater than 3. In this regard, when there exists a plurality of R^(17a), they may be identical or different from each other. Furthermore, when there exist a plurality of R^(18a), they may be identical or different from each other.

Preferably, among R^(14a), R^(15a) and R^(16a) as above, the number of groups represented by the formula (a6) is one in view of the stability of the compound, and the remaining are linear or branched alkylene groups having 1 to 6 carbon atoms of which the terminals may bond to form a ring. In this case, the two alkylene groups described above form a 3 to 9 membered ring including sulfur atom(s). Preferably, the number of atoms to form the ring (including sulfur atom(s)) is 5 or 6.

The substituent, which the alkylene group may have, is exemplified by an oxygen atom (in this case, a carbonyl group is formed together with a carbon atom that constitutes the alkylene group), a hydroxyl group or the like.

Alternatively, the substituent, which the phenyl group may have, is exemplified by a hydroxyl group, a linear or branched alkoxy groups having 1 to 6 carbon atoms, linear or branched alkyl groups having 1 to 6 carbon atoms, or the like.

Examples of suitable cation moiety include those represented by the following formulae (a7) and (a8), and the structure represented by the following formula (a8) is particularly preferable.

The cation moieties, which may be of an iodonium salt or a sulfonium salt, are desirably of a sulfonium salt in view of acid-producing efficiency.

It is, therefore, desirable that the preferable anion moiety of the onium salt having a naphthalene ring at the cation moiety is an anion capable of forming a sulfonium salt.

The anion moiety of the acid generator is exemplified by fluoroalkylsulfonic acid ions, of which hydrogen atom(s) being partially or entirely fluorinated, or aryl sulfonic acid ions.

The alkyl group of the fluoroalkylsulfonic acid ions may be linear, branched or cyclic and have 1 to 20 carbon atoms. Preferably, the carbon number is 1 to 10 in view of bulkiness and diffusion distance of the produced acid. In particular, branched or cyclic groups are preferable due to shorter diffusion length. Also, methyl, ethyl, propyl, butyl, octyl groups and the like are preferable due to being inexpensively synthesizable.

The aryl group of the aryl sulfonic acid ions may be an aryl group having 6 to 20 carbon atoms, and is exemplified by a phenol group or a naphthyl group that may be unsubstituted or substituted with an alkyl group or a halogen atom. In particular, aryl groups having 6 to 10 carbon atoms are preferred since they can be synthesized inexpensively. Specific examples of preferable aryl group include phenyl, toluenesulfonyl, ethylphenyl, naphthyl, methylnaphthyl groups and the like.

When hydrogen atoms in the fluoroalkylsulfonic acid ion or the aryl sulfonic acid ion are partially or entirely substituted with a fluorine atom, the fluorination rate is preferably 10% to 100%, and more preferably 50% to 100%; it is particularly preferable that all hydrogen atoms are each substituted with a fluorine atom in view of higher acid strength. Specific examples thereof include trifluoromethane sulfonate, perfluorobutane sulfonate, perfluorooctane sulfonate, perfluorobenzene sulfonate, and the like.

Among these, the preferable anion moiety is exemplified by those represented by the following formula (a9). R^(20a)SO₃ ⁻  (a9)

In the formula (a9), R^(20a) represents a group represented by the following formula (a10) or (a11), or a group represented by the following formula (a12).

In the formula (a10), x represents an integer of 1 to 4. Also, in the formula (a11), R21a represents a hydrogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms, and y represents an integer of 1 to 3. Of these, trifluoromethane sulfonate, and perfluorobutane sulfonate are preferable in view of safety.

In addition, a nitrogen-containing moiety represented by the following formula (a13) or (a14) may be also be used for the anion moiety.

In the formulae (a13) and (a14), X^(a) represents a linear or branched alkylene group of which at least one hydrogen atom is substituted with a fluorine atom, the carbon number of the alkylene group is 2 to 6, preferably 3 to 5, and most preferably the carbon number is 3. In addition, Y^(a) and Z^(a) each independently represent a linear or branched alkyl group of which at least one hydrogen atom is substituted with a fluorine atom, the number of carbon atoms of the alkyl group is 1 to 10, preferably 1 to 7, and more preferably 1 to 3.

The smaller number of carbon atoms in the alkylene group of X^(a), or in the alkyl group of Y^(a) or Z^(a) is preferred since the solubility into organic solvent is favorable.

In addition, a larger number of hydrogen atoms each substituted by a fluorine atom in the alkylene group of X^(a), or in the alkyl group of Y^(a) or Z^(a) is preferred since the acid strength becomes greater. The percentage of fluorine atoms in the alkylene group or alkyl group, i.e., the fluorination rate is preferably 70 to 100% and more preferably 90 to 100%, and most preferable are perfluoroalkylene or perfluoroalkyl groups in which all of the hydrogen atoms are each substituted with a fluorine atom.

Preferable onium salts having a naphthalene ring at their cation moieties are exemplified by compounds represented by the following formulae (a15) and (a16).

Also, the fifth aspect of the (A)acid generator include bissulfonyldiazomethanes such as bis(p-toluenesulfonyl)diazomethane, bis(1,1-dimethyl ethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane and bis(2,4-dimethylphenylsulfonyl)diazomethane; nitrobenzyl derivatives such as 2-nitrobenzyl p-toluenesulfonate, 2,6-dinitrobenzyl p-toluenesulfonate, nitrobenzyl tosylate, dinitrobenzyl tosylate, nitrobenzyl sulfonate, nitrobenzyl carbonate and dinitrobenzyl carbonate; sulfonates such as pyrogalloltrimesylate, pyrogalloltritosylate, benzyltosylate, benzylsulfonate, N-methylsulfonyloxysuccinimide, N-trichloromethylsulfonyloxysuccinimide, N-phenylsulfonyloxymaleimide and N-methylsulfonyloxyphthalimide; trifluoromethane sulfonates such as N-hydroxyphthalimide and N-hydroxynaphthalimide; onium salts such as diphenyliodonium hexafluorophosphate, (4-methoxyphenyl)phenyliodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium trifluoromethanesulfonate, triphenylsulfonium hexafluorophosphate, (4-methoxyphenyl)diphenylsulfonium trifluoromethanesulfonate and (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate; benzointosylates such as benzointosylate and α-methylbenzointosylate; other diphenyliodonium salts, triphenylsulfonium salts, phenyldiazonium salts, benzylcarbonates and the like.

This (A) acid generator may be used alone, or two or more kinds may be used in combination. Furthermore, the content of the (A) acid generator (A) is preferably adjusted to 0.1% to 10% by mass, and more preferably 0.5% to 3% by mass, relative to the total mass of the photosensitive resin composition. When the amount of the acid generator (A) used is adjusted to the range described above, a photosensitive resin composition that is a uniform solution having satisfactory sensitivity and exhibiting excellent storage stability can be readily prepared.

<(B) Resin>

The (B) resin whose solubility in alkali increases under the action of acid contains an alkali-soluble group protected by an aliphatic acid-dissociable dissolution-inhibiting group and comprises an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group (hereinafter referred to also as “(B-3) acrylic resin”). When the photosensitive resin composition contains an (B-3) acrylic resin, a resist pattern having a favorable rectangular sectional shape can be formed. Note that the (B) resin whose solubility in alkali increases under the action of acid may comprise a resin other than the above (B-3) acrylic resin conventionally blended in a positive-type photosensitive resin composition.

The content of the (B-3) acrylic resin in the total resin components contained in a photosensitive resin composition is preferably 70% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass relative to the total mass of the (B) resin whose solubility in alkali increases under the action of acid and a (C) alkali-soluble resin described below.

Below, as preferred examples of the (B) resin whose solubility in alkali increases under the action of acid, a (B1) novolak resin, a (B-2) polyhydroxystyrene resin and an (B3) acrylic resin (B3) will be described in this order.

[(B1) Novolak Resin]

As the (B1) novolak resin, a resin including the structural unit represented by the following general formula (b1) may be used.

In the formula (b1), R^(1b) represents an acid-dissociable dissolution-inhibiting group, and R^(2b) and R^(3b) each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

The acid-dissociable dissolution-inhibiting group represented by the above R^(1b) is preferably a group represented by the following formula (b2) or (b3), a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, a vinyloxyethyl group, a tetrahydropyranyl group, a tetrahydrofuranyl group, or a trialkylsilyl group.

In the formulae (b2) and (b3), R^(4b) and R^(5b) each independently represent a hydrogen atom, or a linear or branched alkyl group having 1 to 6 carbon atoms, R^(6b) represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, R^(7b) represents a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and o represents 0 or 1.

Examples of the linear or branched alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like. Also, examples of the cyclic alkyl group include a cyclopentyl group, a cyclohexyl group, and the like.

Specific examples of the acid-dissociable dissolution-inhibiting group represented by the formula (b2) include a methoxyethyl group, ethoxyethyl group, n-propoxyethyl group, isopropoxyethyl group, n-butoxyethyl group, isobutoxyethyl group, tert-butoxyethyl group, cyclohexyloxyethyl group, methoxypropyl group, ethoxypropyl group, 1-methoxy-1-methyl-ethyl group, 1-ethoxy-1-methylethyl group, and the like. Furthermore, specific examples of the acid-dissociable dissolution-inhibiting group represented by the formula (b3) include a tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group, and the like. Examples of the trialkylsilyl group include a trimethylsilyl group and tri-tert-butyldimethylsilyl group in which each alkyl group has 1 to 6 carbon atoms.

[(B2) Polyhydroxystyrene Resin]

As the (B2) polyhydroxystyrene resin, a resin including the structural unit represented by the following formula (b4) may be used.

In the formula (b4), R^(8b) represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R^(9b) represents an acid-dissociable dissolution-inhibiting group.

The alkyl group having 1 to 6 carbon atoms may include, for example, linear, branched or cyclic alkyl groups having 1 to 6 carbon atoms. Examples of the linear or branched alkyl group include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group and neopentyl group, and examples of the cyclic alkyl group include a cyclopentyl group and cyclohexyl group.

The acid-dissociable dissolution-inhibiting group represented by the above R^(9b) may be similar to the acid-dissociable dissolution-inhibiting groups exemplified in terms of the above formulae (b2) and (b3).

Furthermore, the (B2) polyhydroxystyrene resin may include another polymerizable compound as a structural unit in order to moderately control physical or chemical properties. The polymerizable compound is exemplified by conventional radical polymerizable compounds and anion polymerizable compounds. Examples of the polymerizable compound include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; methacrylic acid derivatives having a carboxyl group and an ester bond such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid 2-methacryloyloxyethyl phthalic acid and 2-methacryloyloxyethyl hexahydrophthalic acid; (meth)acrylic acid alkyl esters such as methyl(meth)acrylate, ethyl (meth)acrylate and butyl (meth)acrylate; (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; (meth)acrylic acid aryl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate; dicarboxylic acid diesters such as diethyl maleate and dibutyl fumarate; vinyl group-containing aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, vinyltoluene, hydroxystyrene, α-methylhydroxystyrene and α-ethylhydroxystyrene; vinyl group-containing aliphatic compounds such as vinyl acetate; conjugated diolefins such as butadiene and isoprene; nitrile group-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; chlorine-containing polymerizable compounds such as vinyl chloride and vinylidene chloride; and amide bond-containing polymerizable compounds such as acrylamide and methacrylamide.

[(B3) Acrylic Resin]

As described above, the photosensitive resin composition indispensably contains an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group. Accordingly, the (B3) acrylic resin is preferably an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group. The (B-3) acrylic resin that is a preferred resin will be described as a preferred (B3) acrylic resin.

(B-3) Acrylic Resin

The (B-3) acrylic resin comprises a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group. Accordingly, the (B-3) acrylic resin indispensably contains a constituent unit (b-3a) comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit (b-3b) comprising an organic group comprising an aromatic group and an alcoholic hydroxyl group.

(Constituent Unit (b-3a))

The constituent unit (b-3a) comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group will be described. In this case, the “—SO₂-containing cyclic group” refers to a cyclic group having a cyclic group containing a ring comprising —SO₂— in the ring backbone thereof, specifically a cyclic group in which the sulfur atom (S) in —SO₂— forms a part of the ring backbone of the cyclic group. Considering a ring comprising —SO₂— in the ring backbone thereof as the first ring, a group having that ring alone is called a monocyclic group, and a group further having another ring structure is called a polycyclic group regardless of its structure. The —SO₂-containing cyclic group may be monocyclic or polycyclic.

In particular, the —SO₂-containing cyclic group is preferably a cyclic group containing —O—SO₂— in the ring backbone thereof, i.e., a cyclic group containing a sultone ring in which —O—S— in —O—SO₂— forms a part of the ring backbone.

The number of carbon atoms in an —SO₂-containing cyclic group is preferably 3 to 30, more preferably 4 to 20, even more preferably 4 to 15, and in particular preferably 4 to 12. The above number of carbon atoms is the number of carbon atoms constituting a ring backbone, and shall not include the number of carbon atoms in a substituent.

The —SO₂-containing cyclic group may be an —SO₂-containing aliphatic cyclic group or an —SO₂-containing aromatic cyclic group. It is preferably an —SO₂-containing aliphatic cyclic group.

—SO₂-containing aliphatic cyclic groups include a group in which at least one hydrogen atom is removed from an aliphatic hydrocarbon ring where a part of the carbon atoms constituting the ring backbone thereof is(are) substituted with —SO₂— or —O—SO₂. More specifically, they include a group in which at least one hydrogen atom is removed from an aliphatic hydrocarbon ring where —CH₂— constituting the ring backbone thereof is substituted with —SO₂— and a group in which at least one hydrogen atom is removed from an aliphatic hydrocarbon ring where —CH₂—CH₂— constituting the ring backbone thereof is substituted with —O—SO₂—.

The number of carbon atoms in the above alicyclic hydrocarbon ring is preferably 3 to 20, more preferably 3 to 12. The above alicyclic hydrocarbon ring may be polycyclic, or may be monocyclic. As the monocyclic alicyclic hydrocarbon group, preferred is a group in which two hydrogen atoms are removed from monocycloalkane having 3 to 6 carbon atoms. Examples of the above monocycloalkane can include cyclopentane, cyclohexane and the like. As the polycyclic alicyclic hydrocarbon ring, preferred is a group in which two hydrogen atoms are removed from polycycloalkane having 7 to 12 carbon atoms, and specific examples of the above polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like.

The —SO₂-containing cyclic group may have a substituent. Examples of the above substituent include, for example, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxy group, an oxygen atom (═O), —COOR″, —OC(═O)R″, a hydroxyalkyl group, a cyano group and the like.

For an alkyl group as the above substituent, preferred is an alkyl group having 1 to 6 carbon atoms. The above alkyl group is preferably linear or branched. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group and the like. Among these, a methyl group or an ethyl group is preferred, and in particular a methyl group is preferred.

For an alkoxy group as the above substituent, preferred is an alkoxy group having 1 to 6 carbon atoms. The above alkoxy group is preferably linear or branched. Specific examples include a group in which an alkyl groups recited as an alkyl group for the above substituent is attached to the oxygen atom (—O—).

Halogen atoms as the substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like, and a fluorine atom is preferred.

Halogenated alkyl groups for the above substituent include a group in which a part or all of the hydrogen atoms in the above alkyl group is(are) substituted with the above halogen atom(s).

Halogenated alkyl groups as the above substituent include a group in which a part or all of the hydrogen atoms in the alkyl groups recited as an alkyl group for the above substituent is(are) substituted with the above halogen atom(s). As the above halogenated alkyl group, a fluorinated alkyl group is preferred, and a perfluoroalkyl group is particularly preferred.

R″s in the aforementioned —COOR″ and —OC(═O)R″ are either a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms.

In a case where R″ is a linear or branched alkyl group, the number of carbon atoms in the above chain alkyl group is preferably 1 to 10, more preferably 1 to 5, and in particular preferably 1 or 2.

In a case where R″ is a cyclic alkyl group, the number of carbon atoms in the above cyclic alkyl group is 3 to 15, more preferably 4 to 12, and in particular preferably 5 to 10. Specific examples can include a group in which one or more hydrogen atoms are removed from monocycloalkane; and polycycloalkane such as bicycloalkane, tricycloalkane, tetracycloalkane, which are optionally substituted with a fluorine atom or a fluorinated alkyl group. More specific examples include a group in which one or more hydrogen atoms are removed from monocycloalkane such as cyclopentane and cyclohexane; and polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane and tetracyclododecane.

For a hydroxyalkyl group as the above substituent, preferred is a hydroxyalkyl group having 1 to 6 carbon atoms. Specific examples include a group in which at least one of the hydrogen atoms in the alkyl groups recited as an alkyl group for the above substituent is substituted with a hydroxy group.

More specific examples of the —SO₂-containing cyclic group include the groups represented by the following formulae (3-1) to (3-4).

(In the formulae, A′ represents an alkylene group having 1 to 5 carbon atoms optionally comprising an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom; z represents an integer of 0 to 2; R^(10b) represents an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group, or a cyano group; and R″ represents a hydrogen atom or an alkyl group.)

In the above formulae (3-1) to (3-4), A′ represents an alkylene group having 1 to 5 carbon atoms optionally comprising an oxygen atom (—O—) or a sulfur atom (—S—), an oxygen atom or a sulfur atom. As an alkylene group having 1 to 5 carbon atoms in A′, a linear or branched alkylene group is preferred, including a methylene group, an ethylene group, an n-propylene group, an isopropylene group and the like.

In a case where the above alkylene group comprises an oxygen atom or a sulfur atom, specific examples thereof include a group in which —O— or —S— is present at a terminal or between carbon atoms of the above alkylene group, for example, —O—CH₂—, —CH₂—O—CH₂—, —S—CH₂—, —CH₂—S—CH₂—, and the like. As A′, an alkylene group having 1 to 5 carbon atoms or —O— is preferred, and an alkylene group having 1 to 5 carbon atoms is more preferred, and a methylene group is most preferred.

z may be any of 0 to 2, and is most preferably 0. In a case where z is 2, more than one R^(10b) may be the same, or may differ from each other.

Examples of an alkyl group, an alkoxy group, a halogenated alkyl group, —COOR″, —OC(═O)R″ and a hydroxyalkyl group in R^(10b) include those similar to the groups described for the alkyl group, the alkoxy group, the halogenated alkyl group, —COOR″, —OC(═O)R″ and the hydroxyalkyl group, respectively, which are recited as a substituent optionally contained in the —SO₂-containing cyclic group.

Below, specific cyclic groups represented by the above formulae (3-1) to (3-4) will be illustrated. Note that “Ac” in the formulae represents an acetyl group.

As the —SO₂-containing cyclic group, among those shown above, a group represented by the above formula (3-1) is preferred, and at least one selected from the group consisting of the groups represented by any of the aforementioned formulae (3-1-1), (3-1-18), (3-3-1) and (3-4-1) is more preferred, and a group represented by the aforementioned formula (3-1-1) is most preferred.

The “lactone-containing cyclic group” refers to a cyclic group containing a ring (lactone ring) comprising —O—C(═O)— in the ring backbone thereof. Considering the lactone ring as the first ring, a group having that lactone ring alone is called a monocyclic group, and a group further having another ring structure is called a polycyclic group regardless of its structure. The lactone-containing cyclic group may be a monocyclic group, or may be a polycyclic group.

There is no particular limitation on the lactone cyclic group in the constituent unit (b-3), and any can be used. Specifically, lactone-containing monocyclic groups include a group in which one hydrogen atom is removed from 4 to 6 membered ring lactone, a group in which one hydrogen atom is removed from, for example, β-propiono lactone, a group in which one hydrogen atom is removed from, γ-butyrolactone, a group in which one hydrogen atom is removed from δ-valerolactone and the like. Further, lactone-containing polycyclic groups include a group in which one hydrogen atom is removed from bicycloalkane, tricycloalkane and tetracycloalkane having a lactone ring.

There is no particular limitation on the structures in other part in the constituent unit (b-3) as long as it has an —SO₂-containing cyclic group or a lactone-containing cyclic group. However, preferred is at least one constituent unit selected from the group consisting of a constituent unit (b-3-S) derived from an acrylic acid ester comprising an —SO₂-containing cyclic group in which the hydrogen atom attached to the carbon atom in the α position is optionally substituted with a substituent; and a constituent unit (b-3-L) derived from an acrylic acid ester comprising a lactone-containing cyclic group in which the hydrogen atom attached to the carbon atom in the α position is optionally substituted with a substituent.

Constituent Unit (b-3a-S)

More specifically, examples of the constituent unit (b-3a-S) include one represented by the following formula (b-S1).

(In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; and R^(11b) represents an —SO₂-containing cyclic group; and R^(12b) represents a single-bond or divalent linking group.)

In the formula (b-S1), R is similarly defined as above. R^(11b) is similarly defined as in the —SO₂-containing cyclic group described above. R^(12b) may be either a single-bond linking group or a divalent linking group. A divalent linking group is preferred due to the superior effect of the present invention.

There is no particular limitation on the divalent linking group in R^(12b), but suitable groups include a divalent hydrocarbon group optionally having a substituent, a divalent linking group comprising a hetero atom and the like.

For R^(12b), the hydrocarbon group as a divalent linking group may be an aliphatic hydrocarbon group, or may be an aromatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group without aromaticity. The above aliphatic hydrocarbon group may be saturated or may be unsaturated. Usually, a saturated hydrocarbon group is preferred. More specifically, examples of the above aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, an aliphatic hydrocarbon group comprising a ring in the structure thereof and the like.

The number of carbon atoms in the linear or branched aliphatic hydrocarbon group is preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 5.

As the linear aliphatic hydrocarbon group, a linear alkylene group is preferred. Specific examples include a methylene group [—CH₂—], an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], a pentamethylene group [—(CH₂)₅—] and the like.

As the branched aliphatic hydrocarbon group, a branched alkylene group is preferred. Specific examples include alkyl alkylene groups such as alkyl methylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and —C(CH₂CH₃)₂—; alkyl ethylene groups such as —CH(CH₃) CH₂—, —CH(CH₃) CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃) CH₂— and —C(CH₂CH₃)₂—CH₂—; alkyl trimethylene groups such as —CH(CH₃) CH₂CH₂— and —CH₂CH(CH₃) CH₂—; alkyl tetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂— and —CH₂CH(CH₃)CH₂CH₂—; and the like. As an alkyl group in the alkyl alkylene group, a linear alkyl group having 1 to 5 carbon atoms is preferred.

The above linear or branched aliphatic hydrocarbon group may or may not have a substituent (a group or atom other than a hydrogen atom) which substitutes a hydrogen atom. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxo group (═O) and the like.

Examples of the above aliphatic hydrocarbon group comprising a ring in the structure thereof include a cyclic aliphatic hydrocarbon group optionally comprising a hetero atom in the structure (a group in which two hydrogen atoms are removed from an aliphatic hydrocarbon ring); a group in which the above cyclic aliphatic hydrocarbon group is attached to an end of a linear or branched aliphatic hydrocarbon group; a group in which the above cyclic aliphatic hydrocarbon group is present in a linear or branched aliphatic hydrocarbon group along the chain; and the like. Examples of the above linear or branched aliphatic hydrocarbon group include those similar to the above.

The number of carbon atoms in the cyclic aliphatic hydrocarbon group is preferably 3 to 20, more preferably 3 to 12.

The cyclic aliphatic hydrocarbon group may be polycyclic, or may be monocyclic. As the monocyclic aliphatic hydrocarbon group, a group in which two hydrogen atoms are removed from monocycloalkane is preferred. The number of carbon atoms in the above monocycloalkane is preferably 3 to 6. Specific examples include cyclopentane, cyclohexane and the like. As the polycyclic aliphatic hydrocarbon group, a group in which two hydrogen atoms are removed from polycycloalkane is preferred. The number of carbon atoms in the above polycycloalkane is preferably 7 to 12. Specific examples include adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like.

The cyclic aliphatic hydrocarbon group may or may not have a substituent which substitutes a hydrogen atom (a group or atom other than a hydrogen atom). Examples of the above substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxy group, an oxo group (═O) and the like.

For an alkyl group as the above substituent, an alkyl group having 1 to 5 carbon atoms is preferred, and a methyl group, an ethyl group, a propyl group, an n-butyl group and a tert-butyl group are more preferred.

For an alkoxy group as the above substituent, an alkoxy group having 1 to 5 carbon atoms is preferred, and a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group and a tert-butoxy group are more preferred, and a methoxy group and an ethoxy group are particularly preferred.

Halogen atoms as the above substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atoms and the like, and a fluorine atom is preferred.

Halogenated alkyl groups as the above substituent include a group in which a part or all of hydrogen atoms in the aforementioned alkyl group is(are) substituted with the above halogen atom(s).

In the cyclic aliphatic hydrocarbon group, a part of carbon atoms constituting the ring structure thereof may be substituted with —O— or —S—. As the substituent comprising the above hetero atom, preferred are —O—, —C(═O)—O—, —S—, —S(═O)₂— and —S(═O)₂—O—.

The aromatic hydrocarbon group as the divalent hydrocarbon group is a divalent hydrocarbon group having at least one aromatic ring, and may have a substituent. There is no particular limitation on the aromatic ring as long as it is an cyclic conjugated system having a 4n+2 π electrons, and it may be monocyclic or may be polycyclic. The number of carbon atoms in the aromatic ring is preferably 5 to 30, more preferably 5 to 20, even more preferably 6 to 15, and in particular preferably 6 to 12, provided that the number of carbon atoms in a substituent shall not be included in the above number of carbon atoms.

Specifically, aromatic rings include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene and phenanthrene; aromatic heterocycles in which a part of the carbon atoms constituting the above aromatic hydrocarbon ring is(are) substituted with hetero atom(s). Hetero atoms in the aromatic heterocycle include an oxygen atom, a sulfur atom, a nitrogen atom and the like. Specifically, aromatic heterocycles include a pyridine ring, a thiophene ring and the like.

Specific examples of the aromatic hydrocarbon group as a divalent hydrocarbon group include a group in which two hydrogen atoms are removed from the above aromatic hydrocarbon ring or the above aromatic heterocycle (an arylene group or a heteroarylene group); a group in which two hydrogen atoms are removed from an aromatic compound comprising two or more aromatic rings (for example, biphenyl, fluorene and the like); a group in which one hydrogen atom from a group where one hydrogen atom is removed from the above aromatic hydrocarbon ring or the above aromatic heterocycle (an aryl group or a heteroaryl group) is substituted with an alkylene group (for example, a group in which one hydrogen atom is further removed from an aryl group in an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group and a 2-naphthylethyl group); and the like.

The number of carbon atoms in the above alkylene group attached to an aryl group or a heteroaryl group is preferably 1 to 4, more preferably 1 to 2, and in particular preferably 1.

In the above aromatic hydrocarbon group, a hydrogen atom of the above aromatic hydrocarbon group may be substituted with a substituent. For example, a hydrogen atom attached to an aromatic ring in the above aromatic hydrocarbon group may be substituted with a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxy group, an oxo group (═O) and the like.

For an alkyl group as the above substituent, an alkyl group having 1 to 5 carbon atoms is preferred, and a methyl group, an ethyl group, an n-propyl group, an n-butyl group and a tert-butyl group are more preferred.

For an alkoxy group as the above substituent, an alkoxy group having 1 to 5 carbon atoms is preferred, and a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group and a tert-butoxy group are preferred, and a methoxy group and an ethoxy group are more preferred.

Halogen atoms as the above substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like, and a fluorine atom is preferred.

Halogenated alkyl groups as the above substituent include a group in which a part or all of hydrogen atoms in the aforementioned alkyl group is(are) substituted with the above halogen atom(s).

For R^(12b), a hetero atom in the divalent linking group comprising a hetero atom is an atom other than a carbon atom and a hydrogen atom, including, for example, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom and the like.

Specific examples of the divalent linking group comprising a hetero atom include non-hydrocarbon based linking groups such as —O—, —C(═O)—, —C(═O)—O—, —O—C(═O)—O—, —S—, —S(═O)₂—, —S(═O)₂—O—, —NH—, —NH—C(═O)—, —NH—C(═NH)—, ═N—, and combinations of at least one of these non-hydrocarbon based linking groups and a divalent hydrocarbon group and the like. Examples of the above divalent hydrocarbon group include those similar to the aforementioned divalent hydrocarbon groups optionally having a substituent, and linear or branched aliphatic hydrocarbon groups are preferred.

Among those described above, —NH— in —C(═O)—NH—, and H in —NH— and —NH—C(═NH)— may be substituted with a substituent such as an alkyl group or an acyl group, respectively. The number of carbon atoms in the above substituent is preferably 1 to 10, more preferably 1 to 8, and in particular preferably 1 to 5.

As a divalent linking group in R^(12b), a linear or branched alkylene group, an cyclic aliphatic hydrocarbon group or a divalent linking group comprising a hetero atom is particularly preferred.

In a case where the divalent linking group in R^(12b) is a linear or branched alkylene group, the number of carbon atoms in the above alkylene group is preferably 1 to 10, more preferably 1 to 6, in particular preferably 1 to 4, and most preferably 1 to 3. Specific examples include those similar to the linear alkylene groups or branched alkylene groups recited as a linear or branched aliphatic hydrocarbon group in the description of the “divalent hydrocarbon group optionally having a substituent” as the aforementioned divalent linking group.

In a case where the divalent linking group in R^(12b) is an cyclic aliphatic hydrocarbon group, examples of the above cyclic aliphatic hydrocarbon group include those similar to the cyclic aliphatic hydrocarbon groups recited as the “aliphatic hydrocarbon group comprising a ring in the structure” in the description of the “divalent hydrocarbon group optionally having a substituent” as the aforementioned divalent linking group.

As the above cyclic aliphatic hydrocarbon group, particularly preferred is a group in which two or more hydrogen atoms are removed from cyclopentane, cyclohexane, norbornane, isobornane, adamantane, tricyclodecane or tetracyclododecane.

In a case where the divalent linking group in R^(12b) is a divalent linking group comprising a hetero atom, those preferred as the above linking groups include —O—, —C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH— (H may be substituted with a substituent such as an alkyl group or an acyl group), —S—, —S(═O)₂—, —S(═O)₂—O— and a group represented by the formula —Y¹—O—Y²—, —[Y¹—C(═)—O]_(m′)—Y²— or —Y¹—O—C(═O)—Y₂— (wherein Y¹ and Y² are divalent hydrocarbon groups each independently, optionally having a substituent, and O represents an oxygen atom, and m′ is an integer of 0 to 3).

In a case where the divalent linking group in R^(12b) is —NH—, the hydrogen atom in —NH— may be substituted with a substituent such as an alkyl group or an acyl group. The number of carbon atoms in the above substituent (an alkyl group, an acyl group and the like) is preferably 1 to 10, more preferably 1 to 8, and in particular preferably 1 to 5.

Y¹ and Y² in the formula Y¹—O—Y²—, —[Y¹—C(═O)—O]_(m′)—Y²— or —Y¹—O—C(═O)—Y²— are divalent hydrocarbon groups each independently, optionally having a substituent. Examples of the above divalent hydrocarbon group include those similar to the “divalent hydrocarbon group optionally having a substituent” recited in the description of the above divalent linking group.

As Y¹, a linear aliphatic hydrocarbon group is preferred, and a linear alkylene group is more preferred, and a linear alkylene group having 1 to 5 carbon atoms is more preferred, and a methylene group and an ethylene group are particularly preferred.

As Y², a linear or branched aliphatic hydrocarbon group is preferred, and a methylene group, an ethylene group and an alkylmethylene group are more preferred. The alkyl group in the above alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and in particular preferably a methyl group.

In a group represented by the formula —[Y¹—C(═O)—O]_(m′)—Y²—, m′ is an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, and in particular preferably 1. That is, as a group represented by the formula —[Y¹—C(═O)—O]_(m′)—Y²—, a group represented by the formula —Y¹—C(═O)—O—Y²— is particularly preferred. Among these, a group represented by the formula —(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferred. In the above formula, a′ is an integer of 1 to 10, preferably an integer of 1 to 8, more preferably an integer of 1 to 5, even more preferably 1 or 2, and most preferably 1.

b′ is an integer of 1 to 10, preferably an integer of 1 to 8, more preferably an integer of 1 to 5, even more preferably 1 or 2, and most preferably 1.

With regard to the divalent linking group in R^(12b), an organic group comprising a combination of at least one non-hydrocarbon group and a divalent hydrocarbon group is preferred as the divalent linking group comprising a hetero atom. Among these, a linear chain group having an oxygen atom as a hetero atom, for example, a group comprising an ether bond or an ester bond is preferred, and a group represented by the formula —Y¹—O—Y²—, —[Y¹—C(═O)—O]_(m′)—Y²— or —Y¹—O—C(═O)—Y²— is more preferred, and a group represented by the above formula —[Y¹⁻C(O)—O]_(m′)—Y²— or —Y¹—O—C(═O)—Y²— is particularly preferred.

As the divalent linking group in R^(12b), one comprising an alkylene group or an ester bond (—C(═O)—O—) is preferred.

The above alkylene group is preferably a linear or branched alkylene group. Suitable examples of the above linear aliphatic hydrocarbon group include a methylene group [—CH₂—], an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], a pentamethylene group [—(CH₂)₅—] and the like. Suitable examples of the above branched alkylene group include alkyl alkylene groups such as alkyl methylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and —C(CH₂CH₃)₂—; alkyl ethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂— and —C(CH₂CH₃)₂—CH₂—; alkyl trimethylene groups such as —CH(CH₃) CH₂CH₂— and —CH₂CH(CH₃) CH₂—; alkyl tetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂— and —CH₂CH(CH₃) CH₂CH₂—.

As the divalent linking group comprising an ester bond, particularly preferred is a group represented by the formula: —R^(13b)—C(═O)—O— [wherein R^(13b) represents a divalent linking group.]. That is, the constituent unit (b-3a-S) is preferably one represented by the following formula (b-S1-1).

(In the formula, R and R^(11b) are each similar to the above, and R^(13b) represents a divalent linking group.)

There is no particular limitation for R^(13b), including, for example, those similar to the aforementioned divalent linking group in R^(12b). As the divalent linking group in R^(13b), a linear or branched alkylene group, an aliphatic hydrocarbon group comprising a ring in the structure, or a divalent linking group comprising a hetero atom is preferred, and a linear or branched alkylene group or a divalent linking group comprising an oxygen atom as a hetero atom is preferred.

As the linear alkylene group, a methylene group or an ethylene group is preferred, and a methylene group is particularly preferred. As the branched alkylene group, an alkylmethylene group or an alkylethylene group is preferred, and —CH(CH₃)—, —C(CH₃)₂— or —C(CH₃)₂CH₂— is particularly preferred.

As the divalent linking group comprising an oxygen atom, a divalent linking group comprising an ether bond or an ester bond is preferred, and the aforementioned —Y₁—O—Y²—, —[Y¹—C(═O)—O]_(m′)—Y²— or —Y¹—O—C(═O)—Y²— is more preferred. Y¹ and Y² are each independently divalent hydrocarbon groups optionally having a substituent, and m′ is an integer of 0 to 3. Among these, —Y¹—O—C(═O)—Y²— is preferred, and a group represented by —(CH₂)_(c)—O—C(═O)—(CH₂)_(d)— is particularly preferred. c is an integer of 1 to 5, and 1 or 2 is preferred. d is an integer of 1 to 5, and 1 or 2 is preferred.

As the constituent unit (b-3a-S), in particular, one represented by the following formula (b-S1-11) or (b-S1-12) is preferred, and one represented by the formula (b-S1-12) is more preferred.

(In the formulae, R, A′, R^(10b), z and R^(13b) are each the same as the above.)

In the formula (b-S1-11), A′ is preferably a methylene group, an oxygen atom (—O—) or a sulfur atom (—S—).

As R^(13b), preferred is a linear or branched alkylene group or a divalent linking group comprising an oxygen atom. Examples of the linear or branched alkylene group and the divalent linking group comprising an oxygen atom in R^(13b) include those similar to the aforementioned linear or branched alkylene group and the aforementioned divalent linking group comprising an oxygen atom, respectively.

As the constituent unit represented by the formula (b-S1-12), particularly preferred is one represented by the following formula (b-S1-12a) or (b-S1-12b).

(In the formulae, R and A′ are each the same as the above, and c to e are each independently an integer of 1 to 3.) Constituent Unit (b-3a-L)

Examples of the constituent unit (b-3a-L) include, for example, those in which R^(11b) in the aforementioned formula (b-S1) is substituted with a lactone-containing cyclic group, and more specifically include those represented by the following formulae (b-L1) to (b-L5).

(In the formulae, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; R′ represents each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group, and R″ represents a hydrogen atom or an alkyl group; R^(12b) represents a single bond or divalent linking group, and s″ is an integer of 0 to 2; A″ represents an alkylene group having 1 to 5 carbon atoms optionally comprising an oxygen atom or a sulfur atom, an oxygen atom or a sulfur atom; and r is 0 or 1.)

R in the formulae (b-L1) to (b-L5) is the same as the above. Examples of the alkyl group, the alkoxy group, the halogenated alkyl group, —COOR″, —OC(═O)R″ and the hydroxyalkyl group in R′ include those similar to the alkyl group, the alkoxy group, the halogenated alkyl group, —COOR″, —OC(═O)R″ and the hydroxyalkyl group recited as a substituent optionally contained in the —SO₂-containing cyclic group, respectively.

R′ is preferably a hydrogen atom in view of easy industrial availability. The alkyl group in R″ may be any of a linear, branched or cyclic chain. In a case where R″ is a linear or branched alkyl group, the number of carbon atoms is preferably 1 to 10, more preferably 1 to 5. In a case where R″ is a cyclic alkyl group, the number of carbon atoms is preferably 3 to 15, more preferably 4 to 12, and most preferably 5 to 10. Specific examples include a group in which one or more hydrogen atoms are removed from monocycloalkane and polycycloalkane such as tricycloalkane and tetracycloalkane and the like optionally substituted with a fluorine atom or a fluorinated alkyl group. Specific examples include a group in which one or more hydrogen atoms are removed from monocycloalkane such as cyclopentane and cyclohexane; and polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane and tetracyclododecane; and the like. Examples of A″ include those similar to A′ in the aforementioned formula (3-1). A″ is preferably an alkylene group having 1 to 5 carbon atoms, an oxygen atom (—O—) or a sulfur atom (—S—), more preferably an alkylene group having 1 to 5 carbon atoms or —O—. As the alkylene group having 1 to 5 carbon atoms, a methylene group or a dimethylmethylene group is more preferred, and a methylene group is most preferred.

R^(12b) is similar to R^(12b) in the aforementioned formula (b-S1). In the formula (b-L1), s″ is preferably 1 to 2. Below, specific examples of the constituent units represented by the aforementioned formulae (b-L1) to (b-L3) will be illustrated. In each of the following formulae, R^(α) represents a hydrogen atom, a methyl group or a trifluoromethyl group.

As the constituent unit (b-3a-L), at least one selected from the group consisting of the constituent units represented by the aforementioned formulae (b-L1) to (b-L5) is preferred, and at least one selected from the group consisting of the constituent units represented by the formulae (b-L1) to (b-L3) is more preferred, and at least one selected from the group consisting of the constituent units represented by the aforementioned formula (b-L1) or (b-L3) is particularly preferred. Among these, at least one selected from the group consisting of the constituent units represented by the aforementioned formulae (b-L1-1), (b-L1-2), (b-L2-1), (b-L2-7), (b-L2-12), (b-L2-14), (b-L3-1) and (b-L3-5) is preferred.

Further, as the constituent unit (b-3-L), the constituent units represented by following formulae (b-L6) to (b-L7) are also preferred.

R and R^(12b) in the formulae (b-L6) and (b-L7) are the same as the above.

(Constituent Unit (b-3b))

The constituent unit (b-3b) comprising an organic group comprising an aromatic group and an alcoholic hydroxyl group will be described. A pattern having a favorable sectional shape is likely to be formed when the photosensitive resin composition incorporates an (B-3) acrylic resin comprising a combination of the constituent unit (b-3a) and the constituent unit (b-3b).

As long as the constituent unit (b-3b) comprises an organic group comprising an aromatic group and an alcoholic hydroxyl group, the structure of other moieties is not particularly limited. Preferably, the constituent unit (b-3b) is preferably a constituent unit (b-3b-H) derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group and wherein a hydrogen atom bonded to the carbon atom at the α position may be substituted by a substituent. The constituent unit (b-3b-H) will be described later.

In the constituent unit (b-3b), the aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group and is preferably an aromatic hydrocarbon group.

The aromatic group may be of any type without particular limitation as long as the object of the present invention is not impaired. The organic group may be a monovalent group or a divalent or higher group. The aromatic group is preferably a monovalent or divalent aromatic group. The number of aromatic groups in the constituent unit (b-3b) is not particularly limited and may be 1 or 2 or more, preferably 1.

The aromatic hydrocarbon group may be a monocyclic aromatic group, a group formed by condensing two or more aromatic hydrocarbon groups, or a group formed by bonding two or more aromatic hydrocarbon groups through a single bond. The aromatic hydrocarbon group is a group obtained by removing the same number of hydrogen atoms as the valence of the aromatic hydrocarbon group from various aromatic hydrocarbon groups. Preferred aromatic hydrocarbons which provide preferred aromatic hydrocarbon groups include benzene, naphthalene, biphenyl, anthracene, and phenanthrene.

The aromatic heterocyclic group may be of any type without particular limitation as long as the object of the present invention is not impaired. The aromatic heterocyclic group may be a monocyclic group or a polycyclic group. Examples of aromatic heterocyclic rings that provide preferred aromatic heterocyclic groups include pyridine, furan, thiophene, imidazole, pyrazole, oxazole, thiazole, isoxazole, isothiazole, benzoxazole, benzothiazole, and benzimidazole.

The aromatic groups described above may be substituted as long as the object of the present invention is not impaired. Examples of preferred substituents include a halogen atom, a silyl group, a nitro group, a nitroso group, an alkyl group (preferably an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms, an alkylthio group (preferably an alkylthio group having 1 to 6 carbon atoms), an aliphatic acyl group (preferably an aliphatic acyl group having 2 to 6 carbon atoms), and a cyano group. When the aromatic group is substituted, the number of substituents is not particularly limited, and is preferably 1 to 5, more preferably 1 to 3, for example. The aromatic group is preferably unsubstituted.

The organic group having an alcoholic hydroxyl group is not particularly limited as long as the organic group is a group comprising an aliphatic hydrocarbon group containing an alcoholic hydroxyl group. In the organic group containing an alcoholic hydroxyl group, the alcoholic hydroxyl group may be a primary hydroxyl group, a secondary hydroxyl group, or a tertiary hydroxyl group.

The organic group containing an alcoholic hydroxyl group may contain a bond containing a hetero atom, for example, an ether bond (—O—), a carbonyl group (—CO—), an ester bond (—CO—O—), a carbonate bond (—CO—O—CO—), an amino group (—NH—), an amide bond (—CO—NH—), a urethane bond (—NH—CO—NH—), a sulfide bond (—S—), a disulfide bond (—S—S—), and the like. However, the organic group containing an alcoholic hydroxyl group does not contain a lactone ring or an —SO₂-containing ring.

The organic group containing an alcoholic hydroxyl group may be a monovalent group or a divalent or higher group. The organic group containing an alcoholic hydroxyl group is preferably a monovalent or divalent group.

The aromatic group and the organic group containing an alcoholic hydroxyl group may be bonded to each other or may not be bonded to each other, and are preferably bonded to each other. Preferred groups obtained by bonding the aromatic group and the alcoholic hydroxyl group include groups represented by the following formulae (i) to (Viii). —R^(14b)(OH)—O—R^(15b)  (i) —R^(14b)(OH)—CO—O—R^(15b)  (ii) —R^(14b)(OH)—O—CO—R^(15b)  (iii) —R^(14b)(OH)—R^(15b)  (iv) —R^(16b)—O—R^(17b)—OH  (v) —R^(16b)—CO—O—R^(17b)—OH  (vi) —R^(16b)—O—CO—R^(17b)—OH  (vii) —R^(16b)—R^(17b)—OH  (viii)

In the formulae (i) to (viii), R^(14b) is a trivalent aliphatic hydrocarbon group, R^(15b) is a monovalent aromatic group, R^(16b) is a divalent aromatic group, and R^(17b) is a divalent aliphatic hydrocarbon group. For R^(14b) and R^(15b), the aliphatic hydrocarbon group may be of either linear or branched type and is preferably linear. The number of carbon atoms in the aliphatic hydrocarbon group is preferably 2 to 20, more preferably 2 to 10, particularly preferably 2 to 6. For R^(15b) and R^(16b), preferred aromatic groups are as follows. Specifically, for R^(15b), monovalent aromatic groups obtained by removing one hydrogen atom from benzene, naphthalene, biphenyl, anthracene, phenanthrene, pyridine, furan, thiophene, imidazole, pyrazole, oxazole, thiazole, isoxazole, isothiazole, benzoxazole, benzothiazole, or benzimidazole are preferred, and, for R^(16b), divalent aromatic groups obtained by removing two hydrogen atoms from these aromatic compounds are preferred.

Constituent Unit (b-3b-H)

More specifically, examples of constituent units (b-3b-H) include those represented by the following formula (b-H1).

(In the formula (b-H1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; R^(18b) represents a linear or branched aliphatic hydrocarbon group having 2 to 20 carbon atoms; and R^(19b) represents an aromatic hydrocarbon group.)

For R^(18b), the number of carbon atoms in the aliphatic hydrocarbon group is preferably 2 to 10, more preferably 2 to 6. Phenyl, α-naphthyl, β-naphthyl, 4-phenylphenyl, 3-phenylphenyl, and 2-phenylphenyl groups are preferred as R^(19b).

Preferred specific examples of the constituent unit represented by the formula (b-H1) include constituent units represented by the following formulas (b-H1-1) to (b-H1-24).

(Other Constituent Units)

Further, the (B-3) acrylic resin contains an acid-dissociable dissolution-inhibiting group and comprises constituent units represented by the following formulae (b5) to (b7) as constituent units that enhance the solubility of the (B-3) acrylic resin in alkali under the action of acid.

In the formulae (b5) to (b7), R^(20b) and R^(24b) to R^(29b) each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a fluorine atom, or a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms; R^(21b) to R^(23b) each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms, or an aliphatic cyclic group having 5 to 20 carbon atoms; and R^(22b) and R^(23b) may be bonded to each other to form a hydrocarbon ring having 5 to 20 carbon atoms together with the carbon atom to which both the groups are bonded; Y^(b) represents an optionally substituted aliphatic group or alkyl group; p is an integer of 0 to 4; and q is 0 or 1.

Examples of the linear or branched alkyl group include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, and the like. The fluorinated alkyl group refers to the abovementioned alkyl groups of which the hydrogen atoms are partially or entirely substituted with fluorine atoms. Specific examples of aliphatic cyclic groups include groups obtained by removing one or more hydrogen atoms from monocycloalkanes or polycycloalkanes such as bicycloalkanes, tricycloalkanes, and tetracycloalkane. Specifically, groups obtained by removing one hydrogen atom from a monocycloalkane such as cyclopentane, cyclohexane, cycloheptane, or cyclooctane, or a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane may be mentioned. In particular, groups obtained by removing one hydrogen atom from cyclohexane or adamantane (which may further be substituted) are preferred.

When R^(22b) and R^(23b) do not combine with each other to form a hydrocarbon ring, R^(21b), RR^(22b), and R^(23b) preferably represent a linear or branched alkyl group having 2 to 4 carbon atoms, for example, from the viewpoints of a high contrast and favorable resolution and depth of focus. R^(25b), R^(26b), R^(28b), and R^(29b) preferably represent a hydrogen atom or a methyl group.

The above R^(22b) and R^(23b) may form an aliphatic cyclic group having 5 to 20 carbon atoms together with a carbon atom to which the both are attached. Specific examples of the alicyclic group are the groups of monocycloalkanes and polycycloalkanes such as bicycloalkanes, tricycloalkanes and tetracycloalkanes from which at least one hydrogen atom is removed. Specific examples thereof are monocycloalkanes such as cyclopentane, cyclohexane, cycloheptane and cyclooctane and polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane and tetracyclododecane from which at least one hydrogen atom is removed. Particularly preferable are cyclohexane and adamantane from which at least one hydrogen atom is removed (that may further have a substituent).

Further, in a case where an aliphatic cyclic group to be formed with the above R^(22b) and R^(23b) has a substituent on the ring backbone thereof, examples of the substituent include a polar group such as a hydroxy group, a carboxyl group, a cyano group and an oxygen atom (═O), and a linear or branched alkyl group having 1 to 4 carbon atoms. As the polar group, an oxygen atom (═O) is particularly preferred.

The aforementioned Y^(b) is an alicyclic group or an alkyl group; and examples thereof are monocycloalkanes and polycycloalkanes such as bicycloalkanes, tricycloalkanes and tetracycloalkanes from which at least one hydrogen atom is removed. Specific examples thereof are monocycloalkanes such as cyclopentane, cyclohexane, cycloheptane and cyclooctane, and polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane and tetracyclododecane, from which at least one hydrogen atom is removed. Particularly preferable is adamantane from which at least one hydrogen atom is removed (that may further have a substituent).

When the alicyclic group of the abovementioned Y^(b) has a substituent on the ring skeleton, the substituent is exemplified by polar groups such as a hydroxide group, carboxyl group, cyano group and oxygen atom (═O), and linear or branched lower alkyl groups having 1 to 4 carbon atoms. The polar group is preferably an oxygen atom (═O) in particular.

When Y^(b) is an alkyl group, it is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, and more preferably 6 to 15 carbon atoms. Preferably, the alkyl group is an alkoxyalkyl group in particular; and examples of the alkoxyalkyl group include a 1-methoxyethyl group, 1-ethoxyethyl group, 1-n-propoxyethyl group, 1-isopropoxyethyl group, 1-n-butoxyethyl group, 1-isobutoxyethyl group, 1-tert-butoxyethyl group, 1-methoxypropyl group, 1-ethoxypropyl group, 1-methoxy-1-methylethyl group, 1-ethoxy-1-methylethyl group, and the like.

Preferable specific examples of the structural unit represented by the above formula (b5) are those represented by the following formulae (b5-1) to (b5-33).

In the formulae (b5-1) to (b5-33), R^(30b) represents a hydrogen atom or a methyl group.

Preferable specific examples of the structural unit represented by the formula (b6) include those represented by the following formulae (b6-1) to (b6-26).

In the formulae (b6-1) to (b6-26), R^(30b) represents a hydrogen atom or a methyl group.

Preferable specific examples of the structural unit represented by the formula (b7) include those represented by the following formulae (b7-1) to (b7-15).

In the above formula (b7-1) to (b7-15), R^(30b) represents a hydrogen atom or a methyl group.

Among the constituent units represented by the formulae (b5) to (b7) described above, those represented by the formula (b6) are preferred in that they can be easily synthesized and relatively easily sensitized. Further, among the constituent units represented by the formula (b6), those in which Y^(b) is an alkyl group are preferred, and those in which one or both of R^(25b) and R^(26b) are alkyl groups are preferred.

Further, the (B-3) acrylic resin is preferably a resin comprising a copolymer comprising a constituent unit derived from a polymerizable compound having an ether bond together with a constituent unit represented by the above formulae (b5) to (b7).

Illustrative examples of the polymerizable compound having an ether linkage include radical polymerizable compounds such as (meth)acrylic acid derivatives having an ether linkage and an ester linkage, and specific examples thereof include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethylcarbitol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and the like. Also, the polymerizable compound having an ether linkage is preferably, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, or methoxytriethylene glycol (meth)acrylate. These polymerizable compounds may be used alone, or in combinations of two or more thereof.

Furthermore, the (B-3) acrylic resin may contain another polymerizable compound as a structural unit in order to moderately control physical or chemical properties. The polymerizable compound is exemplified by conventional radical polymerizable compounds and anion polymerizable compounds.

Examples of the polymerizable compound include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; methacrylic acid derivatives having a carboxyl group and an ester bond such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid, 2-methacryloyloxyethyl phthalic acid and 2-methacryloyloxyethyl hexahydrophthalic acid; (meth)acrylic acid alkyl esters such as methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate and cyclohexyl(meth)acrylate; (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; (meth)acrylic acid aryl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate; dicarboxylic acid diesters such as diethyl maleate and dibutyl fumarate; vinyl group-containing aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, vinyltoluene, hydroxystyrene, α-methylhydroxystyrene and α-ethylhydroxystyrene; vinyl group-containing aliphatic compounds such as vinyl acetate; conjugated diolefins such as butadiene and isoprene; nitrile group-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; chlorine-containing polymerizable compounds such as vinyl chloride and vinylidene chloride; amide bond-containing polymerizable compounds such as acrylamide and methacrylamide; and the like.

As described above, the (B-3) acrylic resin may comprise a constituent unit derived from a polymerizable compound having a carboxyl group such as the above monocarboxylic acids and dicarboxylic acids. However, it is preferable that the (B-3) acrylic resin does not substantially contain a constituent unit derived from a polymerizable compound containing a carboxyl group, since a resist pattern including a nonresist portion having a favorable footing-free rectangular sectional shape can easily be formed. Specifically, the proportion of a constituent unit derived from a polymerizable compound having a carboxyl group in the (B-3) acrylic resin is preferably 5% by mass or less, more preferably 3% by mass or less, and in particular preferably 1% by mass or less.

Furthermore, examples of the polymerizable compound include (meth)acrylic acid esters having a non-acid-dissociable aliphatic polycyclic group, and vinyl group-containing aromatic compounds. As the non-acid-dissociable aliphatic polycyclic group, particularly, a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, a norbornyl group, and the like are preferred from the viewpoint of easy industrial availability. These aliphatic polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.

Specific examples of the (meth)acrylic acid esters having a non-acid-dissociable aliphatic polycyclic group include compounds having structures represented by the following formulae (b8-1) to (b8-5).

In formulae (b8-1) to (b8-5), R^(31b) represents a hydrogen atom or a methyl group.

As the (B-3) acrylic resin, those comprising 5% by mass or more of the constituent unit (b-3a) comprising a —SO₂-containing cyclic group or a lactone-containing cyclic group are preferred, and those comprising 10% by mass or more are more preferred, and those comprising 10 to 50% by mass are particularly preferred, and those comprising 10 to 40% by mass are most preferred. In a case where the photosensitive resin composition comprises the constituent unit (b-3) comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group in an amount within the range described above, good developmentability and a good pattern shape can be easily achieved simultaneously.

The (B-3) acrylic resin preferably contains 1% by mass or more, more preferably 5% by mass or more, particularly preferably 5 to 50% by mass, most preferably 5 to 30% by mass, of a constituent unit (b-3b) comprising an organic group containing an aromatic group and an alcoholic hydroxyl group. When the photosensitive resin composition contains the constituent unit (b-3b) comprising an organic group containing an aromatic group and an alcoholic hydroxyl group in the above-defined range, a pattern having a favorable shape can easily be formed.

Further, in the (B-3) acrylic resin, a constituent unit represented by the aforementioned formulae (b5) to (b7) is preferably contained in an amount of 5% by mass or more, more preferably 10% by mass or more, and in particular preferably 10 to 50% by mass.

The (B-3) acrylic resin preferably comprises the above constituent unit derived from a polymerizable compound having an ether bond. The content of the constituent unit derived from a polymerizable compound having an ether bond in the (B-3) acrylic resin is preferably 0 to 50% by mass, more preferably 5 to 30% by mass.

The (B-3) acrylic resin preferably comprises the above constituent unit derived from (meth)acrylic acid esters having a non-acid-dissociable aliphatic polycyclic group. The content of the constituent unit derived from (meth)acrylic acid esters having a non-acid-dissociable aliphatic polycyclic group in the (B-3) acrylic resin is preferably 0 to 50% by mass, more preferably 5 to 30% by mass.

As long as the photosensitive resin composition contains a predetermined amount of the (B-3) acrylic resin, an acrylic resin other than the (B-3) acrylic resin described above can also be used as the (B) resin. There is no particular limitation for such an acrylic resin other than the (B-3) acrylic resin as long as it comprises a constituent unit represented by the formulae (b5) to (b7).

The mass-average molecular weight of the (B) resin described above in terms of polystyrene is preferably 10000 to 600000, more preferably 20000 to 400000, and even more preferably 30000 to 300000. A mass-average molecular weight within these ranges allows a photosensitive resin layer to maintain sufficient strength without reducing detachability from a substrate, and can further prevent a swelled profile and crack generation when plating.

It is also preferred that the (B) resin has a dispersivity of no less than 1.05. Dispersivity herein indicates a value of a mass average molecular weight divided by a number average molecular weight. A dispersivity in the range described above can avoid problems with respect to stress resistance on intended plating or possible swelling of metal layers resulting from the plating process.

The content of the (B) resin is preferably 5 to 60% by mass with respect to the total mass of the photosensitive resin composition.

<(C) Alkali-Soluble Resin>

The photosensitive resin composition may further contain a (C) alkali-soluble resin in order to improve crack resistance, if necessary. The alkali-soluble resin as referred to herein may be determined as follows. A solution of the resin to give a resin concentration of 20% by mass (solvent: propylene glycol monomethyl ether acetate) is used to form a resin film having a film thickness of 1 μm on a substrate, and immersed in an aqueous 2.38% by mass TMAH solution for 1 min.

As the (C) alkali-soluble resin, various resins conventionally compounded in a positive-type photosensitive resin composition may be used within a range where the objects of the present invention are not impaired. However, the photosensitive resin composition preferably does not comprise a resin having a carboxyl group as an alkali-soluble group. As the (C) alkali-soluble resin, preferred is at least one resin selected from the group consisting of a (C1) novolak resin, a (C2) polyhydroxystyrene resin and a (C3) acrylic resin.

[(C1) Novolak resin]

The (C1) novolak resin may be prepared by addition condensation between, for example, aromatic compounds having a phenolic hydroxy group (hereinafter, merely referred to as “phenols”) and aldehydes in the presence of an acid catalyst.

Examples of the phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethyl phenol, 3,4,5-trimethyl phenol, p-phenylphenol, resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, phloroglycinol, hydroxydiphenyl, bisphenol A, gallic acid, gallic acid ester, α-naphthol, β-naphthol, and the like. Examples of the aldehydes include formaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, acetaldehyde, and the like. The catalyst used in the addition condensation reaction, which is not specifically limited, is exemplified by hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, etc., in regards to acid catalyst.

The flexibility of the novolak resins can be enhanced still more when o-cresol is used, a hydrogen atom of a hydroxide group in the resins is substituted with other substituents, or bulky aldehydes are used.

The mass average molecular weight [sic] of (C1) novolac resin is not particularly limited as long as the purpose of the present invention is not impaired, but the mass average molecular weight is preferably 1,000 to 50,000.

[(C2) Polyhydroxystyrene Resin]

The hydroxystyrene compound to constitute the (C2) polyhydroxystyrene resin is exemplified by p-hydroxystyrene, α-methylhydroxystyrene, α-ethylhydroxystyrene, and the like.

Among these, the (C2) polyhydroxystyrene resin is preferably prepared to give a copolymer with a styrene resin. The styrene compound to constitute the styrene resin is exemplified by styrene, chlorostyrene, chloromethylstyrene, vinyltoluene, α-methylstyrene, and the like.

The mass average molecular weight of the (C2) polyhydroxystyrene resin is not particularly limited as long as the purpose of the present invention is not impaired, but the mass average molecular weight is preferably 1,000 to 50,000.

[(C3) Acrylic Resin]

It is preferred that the (C3) acrylic resin includes a structural unit derived from a polymerizable compound having an ether linkage and a structural unit derived from a polymerizable compound having a carboxyl group.

Illustrative examples of the polymerizable compound having an ether linkage include (meth)acrylic acid derivatives having an ether linkage and an ester linkage such as 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethylcarbitol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and the like. The polymerizable compound having an ether linkage is preferably, 2-methoxyethyl acrylate, and methoxytriethylene glycol acrylate. These polymerizable compounds may be used alone, or in combinations of two or more.

Illustrative examples of the polymerizable compound having a carboxyl group include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; compounds having a carboxyl group and an ester linkage such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid, 2-methacryloyloxyethyl phthalic acid and 2-methacryloyloxyethyl hexahydrophthalic acid. The polymerizable compound having a carboxyl group is preferably, acrylic acid and methacrylic acid. These polymerizable compounds may be used alone, or in combinations of two or more thereof.

The mass average molecular weight of the (C3) acrylic resin is not particularly limited as long as the purpose of the present invention is not impaired, but the mass average molecular weight is preferably 50,000 to 800,000.

The (C) alkali-soluble resin is used such that the content of the (B-3) acrylic resin containing a constituent unit derived from an acrylic acid ester comprising the aforementioned —SO₂-containing cyclic group or the lactone-containing cyclic group relative to the total mass of the (B) resin and the (C) alkali-soluble resin in a photosensitive resin composition is 70% by mass or more. Therefore, the content of the (C) alkali soluble resin in a photosensitive resin composition is 30% by mass or less relative to the total amount of the above (B) resin resin and the (C) alkali soluble resin, preferably 20% by mass or less, more preferably 10% by mass or less, and in particular preferably 0% by mass. A low content of the (C) alkali soluble resin tends to produce a photosensitive resin composition having superior sensitivity.

<D) Acid-Diffusion Control Agent>

Preferably, a photosensitive resin composition further contains a (D) acid-diffusion control agent in order to improve the formation of a good pattern shape and the post-exposure delay stability of a photosensitive resin film. As the (D) acid-diffusion control agent, a (D1) nitrogen-containing compound is preferred, and if desired, a (D2) organic carboxylic acid, or an oxo acid of phosphorus or derivatives thereof may be further contained.

[(D1) Nitrogen-Containing Compound]

Examples of the (D1) nitrogen-containing compound (E1) include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, tri-n-pentylamine, tribenzylamine, diethanolamine, triethanolamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, ethylenediamine, N,N,N′,N′-tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3,-tetramethylurea, 1,3-diphenylurea, imidazole, benzimidazole, 4-methylimidazole, 8-oxyquinoline, acridine, purine, pyrrolidine, piperidine, 2,4,6-tri(2-pyridyl)-S-triazine, morpholine, 4-methylmorpholine, piperazine, 1,4-dimethylpiperazine, 1,4-diazabicyclo[2.2.2]octane, pyridine and the like. These may be used alone, or in combinations of two or more thereof.

The (D1) nitrogen-containing compound may be used in an amount typically in the range of 0 to 5 parts by mass, and particularly in the range of 0 to 3 parts by mass, with respect to 100 parts by mass of total mass of the (B) resin and the (C) alkali-soluble resin.

[(D2) Organic Carboxylic Acid or Oxo Acid of Phosphorus or Derivative Thereof]

Among the (D2) organic carboxylic acid, or the oxo acid of phosphorus or the derivative thereof, specific preferred examples of the organic carboxylic acid include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like, and salicylic acid is particularly preferred.

Examples of the oxo acid of phosphorus or derivatives thereof include phosphoric acid and derivatives such as esters thereof such as, e.g., phosphoric acid, phosphoric acid di-n-butyl ester, and phosphoric acid diphenyl ester; phosphonic acid and derivatives such as esters thereof such as, e.g., phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester; and phosphinic acid and derivatives such as esters thereof such as, e.g., phosphinic acid and phenylphosphinic acid; and the like. Among these, phosphonic acid is particularly preferred. These may be used alone, or in combinations of two or more thereof.

The (D2) organic carboxylic acid, or the oxo acid of phosphorus or the derivative thereof may be used in an amount typically in the range of 0 to 5 parts by mass, and particularly in the range of 0 to 3 parts by mass, with respect to 100 parts by mass of total mass of the (B) resin and the (C) alkali-soluble resin.

Moreover, in order to form a salt to allow for stabilization, the (D2) organic carboxylic acid, or the oxo acid of phosphorous or the derivative thereof is preferably used in an amount equivalent to that of the (D1) nitrogen-containing compound.

The photosensitive composition contains an (S) organic solvent, for example, for the purpose of preparing coatability. There is no particular limitation on the (S) organic solvent as long as the objects of the present invention are not impaired, and an organic solvent appropriately selected from those conventionally used for positive-type photosensitive resin compositions can be used.

Specific examples of the (S) organic solvent include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; polyhydric alcohols and derivatives thereof, like monomethyl ethers, monoethyl ethers, monopropyl ethers, monobutyl ethers and monophenyl ethers, such as ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol and dipropylene glycol monoacetate; cyclic ethers such as dioxane; esters such as ethyl formate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate, ethylethoxy acetate, methyl methoxypropionate, ethyl ethoxypropionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanate, 3-methoxybutyl acetate and 3-methyl-3-methoxybutyl acetate; aromatic hydrocarbons such as toluene and xylene; and the like. These may be used alone, or as a mixture of two or more thereof.

There is no particular limitation on the content of the (S) organic solvent as long as the objects of the present invention are not impaired. In a case where a photosensitive resin composition is used for a thick-film application in which a photosensitive resin layer obtained by the spin coating method and the like has a film thickness of 10 μm or more, the (S) organic solvent is preferably used in a range where the solid content concentration of the photosensitive resin composition is 20 to 70% by mass, preferably 30 to 55% by mass.

<Method of Preparing Chemically Amplified Positive-Type Photosensitive Resin Composition>

A chemically amplified positive-type photosensitive resin composition is prepared by mixing and stirring the above components by the common method. Machines which can be used for mixing and stirring the above components include dissolvers, homogenizers, 3-roll mills and the like. After uniformly mixing the above components, the resulting mixture may be filtered through a mesh, a membrane filter and the like.

<<Method of Manufacturing Resist Pattern>>

The resist pattern using the photosensitive composition described above may be formed by any method without particular limitation, and a preferred method comprises laminating a photosensitive resin layer on a substrate, the layer comprising the photosensitive resin composition, exposing the photosensitive resin layer through irradiation with an active ray or radiation, and developing the exposed photosensitive layer.

Examples include substrates for an electronic part, those on which a predetermined wire pattern is formed and the like. Examples of the substrate include substrates made of metals such as silicon, silicon nitride, titanium, tantalum, palladium, titanium-tungsten, copper, chromium, iron, and aluminum; and glass substrates. Examples of the material used for the wiring patterns include copper, solder, chromium, aluminum, nickel, and gold.

The photosensitive resin layer is laminated on the substrate, for example, by the following method. Specifically, a liquid photosensitive resin composition is coated onto a substrate, and the coating is heated to remove the solvent and thus to form a photosensitive layer having a desired thickness. The thickness of the photosensitive layer is not particularly limited. The thickness of the photosensitive resin layer is not particularly limited, but is preferably 10 to 150 μm, more preferably 20 to 120 μm, particularly preferably 20 to 100 μm.

As a method of applying a photosensitive resin composition onto a substrate, those such as the spin coating method, the slit coat method, the roll coat method, the screen printing method and the applicator method can be used. Pre-baking is preferably performed on a photosensitive resin layer. The conditions of pre-baking may differ depending on the components in a photosensitive resin composition, the blending ratio, the thickness of a coating film and the like. They are usually about 2 to 60 minutes at 70 to 150° C., preferably 80 to 140° C.

The photosensitive resin layer formed as described above is selectively irradiated (exposed) with an active ray or radiation, for example, an ultraviolet radiation or visible light with a wavelength of 300 to 500 nm through a mask having a predetermined pattern.

Low pressure mercury lamps, high pressure mercury lamps, super high pressure mercury lamps, metal halide lamps, argon gas lasers, etc. can be used for the light source of the radiation. The radiation may include micro waves, infrared rays, visible lights, ultraviolet rays, X-rays, γ-rays, electron beams, proton beams, neutron beams, ion beams, etc. The irradiation dose of the radiation may vary depending on the constituent of the photosensitive resin composition, the film thickness of the photosensitive resin layer, and the like. For example, when an ultra high-pressure mercury lamp is used, the dose may be 100 to 10,000 mJ/cm². The radiation includes a light ray to activate the (A) acid generator in order to generate an acid.

After the exposure, the diffusion of acid is promoted by heating the photosensitive resin layer using a known method to change the alkali solubility of the photosensitive resin layer at an exposed portion in the photosensitive resin film.

Subsequently, the exposed photosensitive resin layer is developed in accordance with a conventionally known method, and an unnecessary portion is dissolved and removed to form a predetermined resist pattern.

At this time, an alkaline aqueous solution is used as a developing solution.

As the developing solution, an aqueous solution of an alkali such as, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo[5.4.0]-7-undecene or 1,5-diazabicyclo[4.3.0]-5-nonane can be used. Also, an aqueous solution prepared by adding an adequate amount of a water-soluble organic solvent such as methanol or ethanol, or a surfactant to the aqueous solution of the alkali can be used as the developing solution.

The developing time may vary depending on the constituent of the photosensitive resin composition, the film thickness of the photosensitive resin layer, and the like. Usually, the developing time is 1 to 30 min. The method of the development may be any one of a liquid-filling method, a dipping method, a paddle method, a spray developing method, and the like.

After development, it is washed with running water for 30 to 90 seconds, and then dried with an air gun, an oven and the like. In this manner, a resist pattern can be produced.

<<Method of Manufacturing Substrate with Template>>

On a substrate with a template for forming a plated article, a resist pattern formed with a photosensitive resin composition is used as a template. A nonresist section in the resist pattern is filled with metal by plating to form a plated article.

When forming a substrate with a template, a metal substrate is used as a substrate. Note that in the metal substrate, the material of a surface on which a plated article is formed is to be a metal. Therefore, the metal substrate may be made entirely of a metal, or at least a portion of the surface on which a plated article is formed is made of a metal. As examples of a preferred metal as a material of a substrate, copper, gold and aluminum are preferred, and copper is more preferred.

The substrate with the template can be manufactured by a method similar to the aforementioned method of manufacturing a thick resist pattern except that the above metal substrate is used as a substrate, and the shape of a nonresist section in the resist pattern is designed according to the shape of a plated article.

<<Method of Manufacturing Plated Article>>

A conductor such as a metal may be embedded, by plating, into a nonresist section (a portion removed with a developing solution) in the template formed by the above method on the substrate to form a plated article, for example, like a contacting terminal such as a bump or a metal post. Note that there is no particular limitation on the method of plate processing, and various conventionally known methods can be used. As a plating liquid, in particular, a solder plating liquid, a copper plating liquid, a gold plating liquid and a nickel plating liquid are suitably used. Finally, the remaining template is removed with a stripping liquid and the like in accordance with a conventional method.

In the above method of manufacturing a plated article, the plated article is formed using a template comprising a nonresist section having a good rectangular cross-sectional shape and formed with a photosensitive resin composition. Therefore, the cross-sectional shape of the plated article formed will also have a good rectangular shape.

EXAMPLES

Below, the present invention will be described in more detail with reference to Examples, but the present invention shall not be limited to these Examples.

Examples 1-8 and Comparative Examples 1-3

In the Examples and Comparative Examples, the following compounds were used as the (A) acid generator.

In the Examples, resins P-1 to P-8 specified in Table 1 were used as the (B) resin whose solubility in alkali increases under the action of acid. In the Comparative Examples, resins P-9 to P-11 specified in Table 1 were used as the (B) resin whose solubility in alkali increases under the action of acid. The constitution of the constituent units in the resins P-1 to P-11 is indicated below as A to I. Numerical values indicated at lower right of each constituent unit refer to the proportion (% by mass) of the constituent units in the resin.

TABLE 1 Constitution of Mass average Dispersivity the constituent units molecular weight (Mw) (Mw/Mn) P-1 A 38,000 2.65 P-2 B 42,000 2.41 P-3 C 42,000 2.72 P-4 D 39,000 2.70 P-5 E 44,000 2.56 P-6 F 40,000 2.73 P-7 C 103,000 3.25 P-8 C 27,000 2.07 P-9 G 45,000 2.80 P-10 H 44,000 2.98 P-11 I 37,000 2.64

In Examples and Comparative Examples, tri-n-pentylamine was used as an acid diffusion control agent.

Photosensitive resin compositions were obtained by dissolving 100 parts by mass of the resin specified in Table 2, 2 parts by mass of the acid generator, and 0.02 parts by mass of the acid diffusion control agent in propylene glycol monomethyl ether acetate to give a solid concentration of 53% by mass. For the photosensitive resin compositions thus obtained, the sectional shape, resolution and sensitivity of the nonresist portion in the resist pattern were evaluated according to the following method.

[Evaluation of Sectional Shape in Nonresist Portion]

The photosensitive resin compositions of Examples 1 to 8 and Comparative Examples 1 to 3 were coated onto an 8-inch copper substrate with a spin coater to form a photosensitive resin layer having a thickness large enough to form a 100 μm-thick resist pattern. The photosensitive resin layer was prebaked at 150° C. for 5 min. After the pre-baking, pattern exposure was carried out by ghi ray using a mask having a hole pattern for the formation of a hole pattern having a diameter of 60 μm and an exposure device Prisma GHI (Ultratech Inc.). Subsequently, the substrate was mounted on a hot plate to perform post-exposure baking (PEB) for 3 min at 100° C. Then, a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) was added dropwise to the photosensitive resin layer and was allowed to stand for 60 sec at 23° C. This procedure was repeated 4 times for development. Thereafter, washing with running water and blowing with nitrogen were carried out to obtain a resist pattern having a contact hole pattern with a diameter of 60 μm.

A cross-section perpendicular to the plane direction of the resist pattern in a nonresist portion (hole) in the resist pattern formed was observed using a scanning microscope, and the maximum diameter CD_(max) and the minimum diameter CD_(min) of holes corresponding to the surface of the substrate were measured. The sectional shape of holes was evaluated by CD_(max)/CD_(min) values based on the following criteria. The sectional shape of the hole is of a more favorable rectangle as the value of CD_(max)/CD_(min) is closer to 1. The results of evaluation for sectional shapes of nonresist portions are shown in Table 2.

Very Good: CD_(max)/CD_(min) is less than 1.1.

Good: CD_(max)/CD_(min) is 1.1 (inclusive) to 1.2 (exclusive).

Fair: CD_(max)/CD_(min) is 1.2 (inclusive) to 1.3 (exclusive).

Bad: CD_(max)/CD_(min) is 1.3 or more.

[Evaluation of Resolution]

Contact hole patterns were formed to evaluate the resolution in the same manner as described above in connection with the method of evaluating the sectional shape of the nonresist portion, except that three types of masks for the formation of hole patterns with 20 μmø, 40 μmø, and 60 μmø were used. The resolution was evaluated based on the following criteria. The results of evaluation of the resolution are shown in Table 2. For Comparative Example 2, holes with 60 μmø could not be formed.

Very Good: Resolution of holes with 20 μmø was possible.

Good: Resolution of holes with 20 μmø was impossible although resolution of holes with 40 μmø was possible.

Bad: Resolution of holes with 40 μmø was impossible.

[Evaluation of Sensitivity]

Contact hole patterns were formed with masks for the formation of hole patterns with 100 μmø while varying exposure dose in the same manner as described above in connection with the method of evaluating the sectional shape of the nonresist portion. In this case, the exposure dose at which resolution of holes with 100 μmø was possible was regarded as sensitivity. The results of evaluation of sensitivity are shown in Table 2.

TABLE 2 Resin Evaluation of (Type/ sectional shape Parts by in nonresist Evaluation of Sensitivity mass) portion resolution (mJ/cm²) Ex. 1 P-1/100 Good Very Good 300 Ex. 2 P-2/100 Good Very Good 500 Ex. 3 P-3/100 Very Good Very Good 500 Ex. 4 P-4/100 Good Good 1500 Ex. 5 P-5/100 Good Very Good 900 Ex. 6 P-6/100 Very Good Very Good 500 Ex. 7 P-7/100 Very Good Good 700 Ex. 8 P-8/100 Very Good Very Good 300 Comp. Ex. 1 P-9/100 Bad Bad 500 Comp. Ex. 2 P-10/100 Bad Bad — Comp. Ex. 3 P-11/100 Bad Bad More than 2000

Examples 1 to 8 demonstrate that, when a photosensitive resin composition comprising an (A) acid generator that produces an acid by being irradiated with an active ray or radiation, a (B) resin whose solubility in alkali increases under the action of acid, and an (S) organic solvent, wherein the (B) resin comprises an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group, is used, a resist pattern comprising a nonresist portion having a favorable rectangular sectional shape can be formed.

Comparison of Comparative Example 1 with Example 3 reveals that, when the (B) resin does not contain a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, a resist pattern comprising a nonresist portion having a favorable rectangular sectional shape is unlikely to be formed, and the resolution decreases.

Comparison of Comparative Example 2 with Example 3 reveals that, when the (B) resin contains a constituent unit derived from an acrylic acid ester containing an alcoholic hydroxyl group and without containing an aromatic group, instead of the constituent unit derived from an acrylic acid ester comprising an organic group containing an aromatic group and an alcoholic hydroxyl group, the resolution is significantly deteriorated, making it difficult to favorably form a pattern per se.

Comparison of Comparative Example 3 with Example 3 reveals that, when the (B) resin contains a constituent unit derived from an acrylic acid ester containing an aromatic group and without containing an alcoholic hydroxyl group, instead of the constituent unit derived from an acrylic acid ester comprising an organic group containing an aromatic group and an alcoholic hydroxyl group, the resolution is significantly deteriorated, making it difficult to form a resist pattern comprising a nonresist portion having a favorable rectangular sectional shape. 

What is claimed is:
 1. A chemically amplified positive-type photosensitive resin composition, comprising: (A) an acid generator that produces an acid by being irradiated with an active ray or radiation; (B) a resin whose solubility in alkali increases under the action of acid; and (S) an organic solvent, wherein the (B) resin whose solubility in alkali increases under the action of acid contains an alkali-soluble group protected by an aliphatic acid-dissociable dissolution-inhibiting group, and comprises an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group, wherein the constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group is represented by the following formula (b-H1):

wherein, in the formula (b-H1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; R^(18b) represents a linear or branched aliphatic hydrocarbon group having 2 to 20 carbon atoms; and R^(19b) represents an aromatic hydrocarbon group.
 2. The chemically amplified positive-type photosensitive resin composition according to claim 1, wherein the proportion of the mass of the (B-3) acrylic resin to the total mass of the resin component contained in the chemically amplified positive-type photosensitive resin composition is not less than 70% by mass.
 3. A method of manufacturing a resist pattern, comprising: laminating a photosensitive resin layer on a substrate, the layer comprising the chemically amplified positive-type photosensitive resin composition according to claim 1; exposing the photosensitive resin layer through irradiation with an active ray or radiation; and developing the exposed photosensitive layer.
 4. A method of manufacturing a plated article, comprising: laminating a photosensitive resin layer on a metal substrate, the layer comprising the chemically amplified positive-type photosensitive resin composition according to claim 1; exposing the photosensitive resin layer through irradiation with an active ray or radiation, developing the exposed photosensitive layer to prepare a template, which is a resist pattern, for plated article formation, and plating a portion of the substrate which is a nonresist section and wherein the exposed photosensitive layer is removed by the developing to form the plated article inside the template.
 5. The method of manufacturing a resist pattern according to claim 3, wherein the substrate is made of metal.
 6. The method of manufacturing a plated article according to claim 4, wherein the method further comprises removing the remaining template after the plating.
 7. A chemically amplified positive-type photosensitive resin composition, comprising: (A) an acid generator that produces an acid by being irradiated with an active ray or radiation; (B) a resin whose solubility in alkali increases under the action of acid; and (S) an organic solvent, wherein the (B) resin whose solubility in alkali increases under the action of acid contains an alkali-soluble group protected by an aliphatic acid-dissociable dissolution-inhibiting group, and comprises an (B-3) acrylic resin comprising a constituent unit derived from an acrylic acid ester comprising an —SO₂-containing cyclic group or a lactone-containing cyclic group, and a constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group, and the (A) acid generator that produces an acid by being irradiated with an active ray or radiation comprises a fluorinated alkylfluorophosphoric acid anion represented by the following formula (a17): [(R^(3a))_(j)PF_(6-j)]⁻  (a17) wherein, in the formula (a17), R^(3a) represents an alkyl group having 80% or more of the hydrogen atoms substituted by fluorine atoms, j represents the number of R^(3a)s and is an integer from 1 to 5, and R^(3a)s in the number of j may be respectively identical to or different from each other.
 8. The chemically amplified positive-type photosensitive resin composition according to claim 7, wherein the constituent unit derived from an acrylic acid ester containing an organic group comprising an aromatic group and an alcoholic hydroxyl group is represented by the following formula (b-H1):

wherein, in the formula (b-H1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; R^(18b) represents a linear or branched aliphatic hydrocarbon group having 2 to 20 carbon atoms; and R^(19b) represents an aromatic hydrocarbon group.
 9. The chemically amplified positive-type photosensitive resin composition according to claim 7, wherein the proportion of the mass of the (B-3) acrylic resin to the total mass of the resin component contained in the chemically amplified positive-type photosensitive resin composition is not less than 70% by mass.
 10. A method of manufacturing a resist pattern, comprising: laminating a photosensitive resin layer on a substrate, the layer comprising the chemically amplified positive-type photosensitive resin composition according to claim 7; exposing the photosensitive resin layer through irradiation with an active ray or radiation; and developing the exposed photosensitive layer.
 11. A method of manufacturing a plated article, comprising: laminating a photosensitive resin layer on a metal substrate, the layer comprising the chemically amplified positive-type photosensitive resin composition according to claim 7; exposing the photosensitive resin layer through irradiation with an active ray or radiation, developing the exposed photosensitive layer to prepare a template, which is a resist pattern, for plated article formation, and plating a portion of the substrate which is nonresist section and where the exposed photosensitive layer is removed by the developing to form the plated article inside the template.
 12. The method of manufacturing a resist pattern according to claim 10, wherein the substrate is made of metal.
 13. The method of manufacturing a plated article according to claim 11, wherein the method further comprises removing the remaining template after the plating. 